diff --git a/tests/baselines/reference/discriminatedUnionTypes2.errors.txt b/tests/baselines/reference/discriminatedUnionTypes2.errors.txt
new file mode 100644
index 00000000000..c50f7a2767a
--- /dev/null
+++ b/tests/baselines/reference/discriminatedUnionTypes2.errors.txt
@@ -0,0 +1,86 @@
+tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(27,30): error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
+  Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
+tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(32,11): error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
+  Property 'b' does not exist on type '{ a: T; c: number; }'.
+
+
+==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (2 errors) ====
+    function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+        if (x.kind === false) {
+            x.a;
+        }
+        else if (x.kind === true) {
+            x.b;
+        }
+        else {
+            x.c;
+        }
+    }
+    
+    function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+        switch (x.kind) {
+            case false:
+                x.a;
+                break;
+            case true:
+                x.b;
+                break;
+            default:
+                x.c;
+        }
+    }
+    
+    function f13(x: { a: null; b: string } | { a: string, c: number }) {
+        x = { a: null, b: "foo", c: 4};  // Error
+                                 ~~~~
+!!! error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
+!!! error TS2322:   Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
+    }
+    
+    function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
+        if (x.a === 0) {
+            x.b;  // Error
+              ~
+!!! error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
+!!! error TS2339:   Property 'b' does not exist on type '{ a: T; c: number; }'.
+        }
+    }
+    
+    type Result<T> = { error?: undefined, value: T } | { error: Error };
+    
+    function f15(x: Result<number>) {
+        if (!x.error) {
+            x.value;
+        }
+        else {
+            x.error.message;
+        }
+    }
+    
+    f15({ value: 10 });
+    f15({ error: new Error("boom") });
+    
+    // Repro from #24193
+    
+    interface WithError {
+        error: Error
+        data: null
+    }
+    
+    interface WithoutError<Data> {
+        error: null
+        data: Data
+    }
+    
+    type DataCarrier<Data> = WithError | WithoutError<Data>
+    
+    function f20<Data>(carrier: DataCarrier<Data>) {
+        if (carrier.error === null) {
+            const error: null = carrier.error
+            const data: Data = carrier.data
+        } else {
+            const error: Error = carrier.error
+            const data: null = carrier.data
+        }
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/discriminatedUnionTypes2.js b/tests/baselines/reference/discriminatedUnionTypes2.js
new file mode 100644
index 00000000000..e2b5d99ddcd
--- /dev/null
+++ b/tests/baselines/reference/discriminatedUnionTypes2.js
@@ -0,0 +1,128 @@
+//// [discriminatedUnionTypes2.ts]
+function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+    if (x.kind === false) {
+        x.a;
+    }
+    else if (x.kind === true) {
+        x.b;
+    }
+    else {
+        x.c;
+    }
+}
+
+function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+    switch (x.kind) {
+        case false:
+            x.a;
+            break;
+        case true:
+            x.b;
+            break;
+        default:
+            x.c;
+    }
+}
+
+function f13(x: { a: null; b: string } | { a: string, c: number }) {
+    x = { a: null, b: "foo", c: 4};  // Error
+}
+
+function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
+    if (x.a === 0) {
+        x.b;  // Error
+    }
+}
+
+type Result<T> = { error?: undefined, value: T } | { error: Error };
+
+function f15(x: Result<number>) {
+    if (!x.error) {
+        x.value;
+    }
+    else {
+        x.error.message;
+    }
+}
+
+f15({ value: 10 });
+f15({ error: new Error("boom") });
+
+// Repro from #24193
+
+interface WithError {
+    error: Error
+    data: null
+}
+
+interface WithoutError<Data> {
+    error: null
+    data: Data
+}
+
+type DataCarrier<Data> = WithError | WithoutError<Data>
+
+function f20<Data>(carrier: DataCarrier<Data>) {
+    if (carrier.error === null) {
+        const error: null = carrier.error
+        const data: Data = carrier.data
+    } else {
+        const error: Error = carrier.error
+        const data: null = carrier.data
+    }
+}
+
+
+//// [discriminatedUnionTypes2.js]
+"use strict";
+function f10(x) {
+    if (x.kind === false) {
+        x.a;
+    }
+    else if (x.kind === true) {
+        x.b;
+    }
+    else {
+        x.c;
+    }
+}
+function f11(x) {
+    switch (x.kind) {
+        case false:
+            x.a;
+            break;
+        case true:
+            x.b;
+            break;
+        default:
+            x.c;
+    }
+}
+function f13(x) {
+    x = { a: null, b: "foo", c: 4 }; // Error
+}
+function f14(x) {
+    if (x.a === 0) {
+        x.b; // Error
+    }
+}
+function f15(x) {
+    if (!x.error) {
+        x.value;
+    }
+    else {
+        x.error.message;
+    }
+}
+f15({ value: 10 });
+f15({ error: new Error("boom") });
+function f20(carrier) {
+    if (carrier.error === null) {
+        var error = carrier.error;
+        var data = carrier.data;
+    }
+    else {
+        var error = carrier.error;
+        var data = carrier.data;
+    }
+}
diff --git a/tests/baselines/reference/discriminatedUnionTypes2.symbols b/tests/baselines/reference/discriminatedUnionTypes2.symbols
new file mode 100644
index 00000000000..38cfcb0b23a
--- /dev/null
+++ b/tests/baselines/reference/discriminatedUnionTypes2.symbols
@@ -0,0 +1,227 @@
+=== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts ===
+function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+>f10 : Symbol(f10, Decl(discriminatedUnionTypes2.ts, 0, 0))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 75))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))
+
+    if (x.kind === false) {
+>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18), Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18), Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
+
+        x.a;
+>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
+    }
+    else if (x.kind === true) {
+>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
+
+        x.b;
+>x.b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
+    }
+    else {
+        x.c;
+>x.c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))
+    }
+}
+
+function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+>f11 : Symbol(f11, Decl(discriminatedUnionTypes2.ts, 10, 1))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 47))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 75))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))
+
+    switch (x.kind) {
+>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18), Decl(discriminatedUnionTypes2.ts, 12, 47), Decl(discriminatedUnionTypes2.ts, 12, 75))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
+>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18), Decl(discriminatedUnionTypes2.ts, 12, 47), Decl(discriminatedUnionTypes2.ts, 12, 75))
+
+        case false:
+            x.a;
+>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))
+
+            break;
+        case true:
+            x.b;
+>x.b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))
+
+            break;
+        default:
+            x.c;
+>x.c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))
+    }
+}
+
+function f13(x: { a: null; b: string } | { a: string, c: number }) {
+>f13 : Symbol(f13, Decl(discriminatedUnionTypes2.ts, 23, 1))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 25, 13))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 25, 17))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 25, 26))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 25, 42))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 25, 53))
+
+    x = { a: null, b: "foo", c: 4};  // Error
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 25, 13))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 26, 9))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 26, 18))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 26, 28))
+}
+
+function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
+>f14 : Symbol(f14, Decl(discriminatedUnionTypes2.ts, 27, 1))
+>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 29, 13))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20))
+>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 29, 26))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 42))
+>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 29, 13))
+>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 29, 48))
+
+    if (x.a === 0) {
+>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20), Decl(discriminatedUnionTypes2.ts, 29, 42))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
+>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20), Decl(discriminatedUnionTypes2.ts, 29, 42))
+
+        x.b;  // Error
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
+    }
+}
+
+type Result<T> = { error?: undefined, value: T } | { error: Error };
+>Result : Symbol(Result, Decl(discriminatedUnionTypes2.ts, 33, 1))
+>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 35, 12))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 18))
+>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
+>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 35, 12))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+function f15(x: Result<number>) {
+>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
+>Result : Symbol(Result, Decl(discriminatedUnionTypes2.ts, 33, 1))
+
+    if (!x.error) {
+>x.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52), Decl(discriminatedUnionTypes2.ts, 35, 18))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52), Decl(discriminatedUnionTypes2.ts, 35, 18))
+
+        x.value;
+>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
+>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
+    }
+    else {
+        x.error.message;
+>x.error.message : Symbol(Error.message, Decl(lib.es5.d.ts, --, --))
+>x.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
+>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
+>message : Symbol(Error.message, Decl(lib.es5.d.ts, --, --))
+    }
+}
+
+f15({ value: 10 });
+>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
+>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 46, 5))
+
+f15({ error: new Error("boom") });
+>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 47, 5))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+// Repro from #24193
+
+interface WithError {
+>WithError : Symbol(WithError, Decl(discriminatedUnionTypes2.ts, 47, 34))
+
+    error: Error
+>error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+    data: null
+>data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
+}
+
+interface WithoutError<Data> {
+>WithoutError : Symbol(WithoutError, Decl(discriminatedUnionTypes2.ts, 54, 1))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 56, 23))
+
+    error: null
+>error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))
+
+    data: Data
+>data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 56, 23))
+}
+
+type DataCarrier<Data> = WithError | WithoutError<Data>
+>DataCarrier : Symbol(DataCarrier, Decl(discriminatedUnionTypes2.ts, 59, 1))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 61, 17))
+>WithError : Symbol(WithError, Decl(discriminatedUnionTypes2.ts, 47, 34))
+>WithoutError : Symbol(WithoutError, Decl(discriminatedUnionTypes2.ts, 54, 1))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 61, 17))
+
+function f20<Data>(carrier: DataCarrier<Data>) {
+>f20 : Symbol(f20, Decl(discriminatedUnionTypes2.ts, 61, 55))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>DataCarrier : Symbol(DataCarrier, Decl(discriminatedUnionTypes2.ts, 59, 1))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))
+
+    if (carrier.error === null) {
+>carrier.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 51, 21), Decl(discriminatedUnionTypes2.ts, 56, 30))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 51, 21), Decl(discriminatedUnionTypes2.ts, 56, 30))
+
+        const error: null = carrier.error
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 65, 13))
+>carrier.error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))
+
+        const data: Data = carrier.data
+>data : Symbol(data, Decl(discriminatedUnionTypes2.ts, 66, 13))
+>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))
+>carrier.data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))
+
+    } else {
+        const error: Error = carrier.error
+>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 68, 13))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>carrier.error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))
+
+        const data: null = carrier.data
+>data : Symbol(data, Decl(discriminatedUnionTypes2.ts, 69, 13))
+>carrier.data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
+>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
+>data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
+    }
+}
+
diff --git a/tests/baselines/reference/discriminatedUnionTypes2.types b/tests/baselines/reference/discriminatedUnionTypes2.types
new file mode 100644
index 00000000000..b654fc1a78d
--- /dev/null
+++ b/tests/baselines/reference/discriminatedUnionTypes2.types
@@ -0,0 +1,241 @@
+=== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts ===
+function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+>f10 : (x: { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }) => void
+>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
+>kind : false
+>false : false
+>a : string
+>kind : true
+>true : true
+>b : string
+>kind : string
+>c : string
+
+    if (x.kind === false) {
+>x.kind === false : boolean
+>x.kind : string | boolean
+>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
+>kind : string | boolean
+>false : false
+
+        x.a;
+>x.a : string
+>x : { kind: false; a: string; }
+>a : string
+    }
+    else if (x.kind === true) {
+>x.kind === true : boolean
+>x.kind : string | true
+>x : { kind: true; b: string; } | { kind: string; c: string; }
+>kind : string | true
+>true : true
+
+        x.b;
+>x.b : string
+>x : { kind: true; b: string; }
+>b : string
+    }
+    else {
+        x.c;
+>x.c : string
+>x : { kind: string; c: string; }
+>c : string
+    }
+}
+
+function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
+>f11 : (x: { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }) => void
+>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
+>kind : false
+>false : false
+>a : string
+>kind : true
+>true : true
+>b : string
+>kind : string
+>c : string
+
+    switch (x.kind) {
+>x.kind : string | boolean
+>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
+>kind : string | boolean
+
+        case false:
+>false : false
+
+            x.a;
+>x.a : string
+>x : { kind: false; a: string; }
+>a : string
+
+            break;
+        case true:
+>true : true
+
+            x.b;
+>x.b : string
+>x : { kind: true; b: string; }
+>b : string
+
+            break;
+        default:
+            x.c;
+>x.c : string
+>x : { kind: string; c: string; }
+>c : string
+    }
+}
+
+function f13(x: { a: null; b: string } | { a: string, c: number }) {
+>f13 : (x: { a: null; b: string; } | { a: string; c: number; }) => void
+>x : { a: null; b: string; } | { a: string; c: number; }
+>a : null
+>null : null
+>b : string
+>a : string
+>c : number
+
+    x = { a: null, b: "foo", c: 4};  // Error
+>x = { a: null, b: "foo", c: 4} : { a: null; b: string; c: number; }
+>x : { a: null; b: string; } | { a: string; c: number; }
+>{ a: null, b: "foo", c: 4} : { a: null; b: string; c: number; }
+>a : null
+>null : null
+>b : string
+>"foo" : "foo"
+>c : number
+>4 : 4
+}
+
+function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
+>f14 : <T>(x: { a: 0; b: string; } | { a: T; c: number; }) => void
+>x : { a: 0; b: string; } | { a: T; c: number; }
+>a : 0
+>b : string
+>a : T
+>c : number
+
+    if (x.a === 0) {
+>x.a === 0 : boolean
+>x.a : 0 | T
+>x : { a: 0; b: string; } | { a: T; c: number; }
+>a : 0 | T
+>0 : 0
+
+        x.b;  // Error
+>x.b : any
+>x : { a: 0; b: string; } | { a: T; c: number; }
+>b : any
+    }
+}
+
+type Result<T> = { error?: undefined, value: T } | { error: Error };
+>Result : Result<T>
+>error : undefined
+>value : T
+>error : Error
+
+function f15(x: Result<number>) {
+>f15 : (x: Result<number>) => void
+>x : Result<number>
+
+    if (!x.error) {
+>!x.error : boolean
+>x.error : Error | undefined
+>x : Result<number>
+>error : Error | undefined
+
+        x.value;
+>x.value : number
+>x : { error?: undefined; value: number; }
+>value : number
+    }
+    else {
+        x.error.message;
+>x.error.message : string
+>x.error : Error
+>x : { error: Error; }
+>error : Error
+>message : string
+    }
+}
+
+f15({ value: 10 });
+>f15({ value: 10 }) : void
+>f15 : (x: Result<number>) => void
+>{ value: 10 } : { value: number; }
+>value : number
+>10 : 10
+
+f15({ error: new Error("boom") });
+>f15({ error: new Error("boom") }) : void
+>f15 : (x: Result<number>) => void
+>{ error: new Error("boom") } : { error: Error; }
+>error : Error
+>new Error("boom") : Error
+>Error : ErrorConstructor
+>"boom" : "boom"
+
+// Repro from #24193
+
+interface WithError {
+    error: Error
+>error : Error
+
+    data: null
+>data : null
+>null : null
+}
+
+interface WithoutError<Data> {
+    error: null
+>error : null
+>null : null
+
+    data: Data
+>data : Data
+}
+
+type DataCarrier<Data> = WithError | WithoutError<Data>
+>DataCarrier : DataCarrier<Data>
+
+function f20<Data>(carrier: DataCarrier<Data>) {
+>f20 : <Data>(carrier: DataCarrier<Data>) => void
+>carrier : DataCarrier<Data>
+
+    if (carrier.error === null) {
+>carrier.error === null : boolean
+>carrier.error : Error | null
+>carrier : DataCarrier<Data>
+>error : Error | null
+>null : null
+
+        const error: null = carrier.error
+>error : null
+>null : null
+>carrier.error : null
+>carrier : WithoutError<Data>
+>error : null
+
+        const data: Data = carrier.data
+>data : Data
+>carrier.data : Data
+>carrier : WithoutError<Data>
+>data : Data
+
+    } else {
+        const error: Error = carrier.error
+>error : Error
+>carrier.error : Error
+>carrier : WithError
+>error : Error
+
+        const data: null = carrier.data
+>data : null
+>null : null
+>carrier.data : null
+>carrier : WithError
+>data : null
+    }
+}
+