From 07da12167edafb9927efaf64d5541408e2c1b1c4 Mon Sep 17 00:00:00 2001
From: Sheetal Nandi <shkamat@microsoft.com>
Date: Fri, 20 Jul 2018 12:20:39 -0700
Subject: [PATCH] Reflect getCurrentProgram as Program|undefined in the
 ResolutionHostCache If there were any exceptions, the getCurrentProgram might
 return undefined so this is defensive check for program Fixes #25765

---
 src/compiler/resolutionCache.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/compiler/resolutionCache.ts b/src/compiler/resolutionCache.ts
index d05d8350508..7eea82a1fc0 100644
--- a/src/compiler/resolutionCache.ts
+++ b/src/compiler/resolutionCache.ts
@@ -52,7 +52,7 @@ namespace ts {
         getGlobalCache?(): string | undefined;
         writeLog(s: string): void;
         maxNumberOfFilesToIterateForInvalidation?: number;
-        getCurrentProgram(): Program;
+        getCurrentProgram(): Program | undefined;
     }
 
     interface DirectoryWatchesOfFailedLookup {
@@ -497,7 +497,8 @@ namespace ts {
         }
 
         function watchFailedLookupLocationOfNonRelativeModuleResolutions(resolutions: ResolutionWithFailedLookupLocations[], name: string) {
-            const updateResolution = resolutionHost.getCurrentProgram().getTypeChecker().tryFindAmbientModuleWithoutAugmentations(name) ?
+            const program = resolutionHost.getCurrentProgram();
+            const updateResolution = program && program.getTypeChecker().tryFindAmbientModuleWithoutAugmentations(name) ?
                 setRefCountToUndefined : watchFailedLookupLocationOfResolution;
             resolutions.forEach(updateResolution);
         }