From 30da23fa7770cc8bac06f776522ddfa79df8b4a5 Mon Sep 17 00:00:00 2001
From: uniqueiniquity <blichtman623@gmail.com>
Date: Thu, 30 Nov 2017 10:22:41 -0800
Subject: [PATCH 1/4] Handle failure to properly resolve type reference
 directives

---
 src/compiler/checker.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 405fd11f138..c797200bff2 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -25000,10 +25000,11 @@ namespace ts {
                 // populate reverse mapping: file path -> type reference directive that was resolved to this file
                 fileToDirective = createMap<string>();
                 resolvedTypeReferenceDirectives.forEach((resolvedDirective, key) => {
-                    if (!resolvedDirective) {
+                    if (!resolvedDirective || !resolvedDirective.resolvedFileName) {
                         return;
                     }
                     const file = host.getSourceFile(resolvedDirective.resolvedFileName);
+                    Debug.assert(!!file, `Resolved filename ${resolvedDirective.resolvedFileName} did not map to existing source file. Consider enabling --preserveSymlinks if appropriate`); // tslint:disable-line
                     fileToDirective.set(file.path, key);
                 });
             }

From 1fc6675a2973b2ad361ab3bf4c946bc48baeeb95 Mon Sep 17 00:00:00 2001
From: uniqueiniquity <blichtman623@gmail.com>
Date: Wed, 6 Dec 2017 14:40:59 -0800
Subject: [PATCH 2/4] Allow for undefined return from
 TypeCheckerHost.getSourceFile to correspond with implementation

---
 src/compiler/types.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f6ca2f45d34..6ab0f5543ec 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2736,7 +2736,7 @@ namespace ts {
         getCompilerOptions(): CompilerOptions;
 
         getSourceFiles(): ReadonlyArray<SourceFile>;
-        getSourceFile(fileName: string): SourceFile;
+        getSourceFile(fileName: string): SourceFile | undefined;
         getResolvedTypeReferenceDirectives(): ReadonlyMap<ResolvedTypeReferenceDirective>;
     }
 

From 46fa477c156f9771e8be4cb70eff3a1458cb7962 Mon Sep 17 00:00:00 2001
From: uniqueiniquity <blichtman623@gmail.com>
Date: Fri, 19 Jan 2018 16:22:09 -0800
Subject: [PATCH 3/4] Move assertion to realpath evaluation

---
 src/compiler/checker.ts            | 1 -
 src/compiler/moduleNameResolver.ts | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index c797200bff2..41e1ed99dc6 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -25004,7 +25004,6 @@ namespace ts {
                         return;
                     }
                     const file = host.getSourceFile(resolvedDirective.resolvedFileName);
-                    Debug.assert(!!file, `Resolved filename ${resolvedDirective.resolvedFileName} did not map to existing source file. Consider enabling --preserveSymlinks if appropriate`); // tslint:disable-line
                     fileToDirective.set(file.path, key);
                 });
             }
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index f72876bd5fc..e0acf43eadf 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -782,6 +782,7 @@ namespace ts {
         if (traceEnabled) {
             trace(host, Diagnostics.Resolving_real_path_for_0_result_1, path, real);
         }
+        Debug.assert(host.fileExists(real), `${path} linked to non-existing file ${real}`); // tslint:disable-line
         return real;
     }
 

From 4a877897792ec3ec58ab06991d314af03dc37181 Mon Sep 17 00:00:00 2001
From: uniqueiniquity <blichtman623@gmail.com>
Date: Fri, 19 Jan 2018 16:40:52 -0800
Subject: [PATCH 4/4] Fix typo in message

---
 src/compiler/moduleNameResolver.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index e0acf43eadf..4f893302693 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -782,7 +782,7 @@ namespace ts {
         if (traceEnabled) {
             trace(host, Diagnostics.Resolving_real_path_for_0_result_1, path, real);
         }
-        Debug.assert(host.fileExists(real), `${path} linked to non-existing file ${real}`); // tslint:disable-line
+        Debug.assert(host.fileExists(real), `${path} linked to nonexistent file ${real}`); // tslint:disable-line
         return real;
     }