From 95506858d83c3096ce4eaa9bfa354a97002a8a4c Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Thu, 21 Jul 2022 13:27:28 -0700
Subject: [PATCH] Protect watcher from double close

---
 src/compiler/sys.ts | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 701276b9da920..e293932b0b463 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -1088,14 +1088,16 @@ namespace ts {
                 lastDirectoryPart = lastDirectoryPartWithDirectorySeparator.slice(directorySeparator.length);
             }
             /** Watcher for the file system entry depending on whether it is missing or present */
-            let watcher = !fileSystemEntryExists(fileOrDirectory, entryKind) ?
+            let watcher: FileWatcher | undefined = !fileSystemEntryExists(fileOrDirectory, entryKind) ?
                 watchMissingFileSystemEntry() :
                 watchPresentFileSystemEntry();
             return {
                 close: () => {
                     // Close the watcher (either existing file system entry watcher or missing file system entry watcher)
-                    watcher.close();
-                    watcher = undefined!;
+                    if (watcher) {
+                        watcher.close();
+                        watcher = undefined;
+                    }
                 }
             };