Merge pull request #15229 from Microsoft/Fix15220

Fix #15220: Check for file on diagnostics before getting line map

tests/baselines/reference/checkJsFiles_noErrorLocation.errors.txt

@@ -0,0 +1,25 @@
+tests/cases/compiler/a.js(14,5): error TS2424: Class 'A' defines instance member function 'foo', but extended class 'B' defines it as instance member property.
+
+
+==== tests/cases/compiler/a.js (1 errors) ====
+    // @ts-check
+    class A {
+      constructor() {
+    
+      }
+      foo() {
+        return 4;
+      }
+    }
+    
+    class B extends A {
+      constructor() {
+        super();
+        this.foo = () => 3;
+        ~~~~~~~~~~~~~~~~~~
+!!! error TS2424: Class 'A' defines instance member function 'foo', but extended class 'B' defines it as instance member property.
+      }
+    }
+    
+    const i = new B();
+    i.foo();

tests/cases/compiler/checkJsFiles_noErrorLocation.ts

@@ -0,0 +1,24 @@
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+
+// @fileName: a.js
+// @ts-check
+class A {
+  constructor() {
+
+  }
+  foo() {
+    return 4;
+  }
+}
+
+class B extends A {
+  constructor() {
+    super();
+    this.foo = () => 3;
+  }
+}
+
+const i = new B();
+i.foo();