strcit null checks

#60565

src/tsconfig.strictNullChecks.json

@@ -78,6 +78,7 @@
 		"./vs/base/common/winjs.base.d.ts",
 		"./vs/base/common/winjs.polyfill.promise.ts",
 		"./vs/base/common/worker/simpleWorker.ts",
+		"./vs/workbench/common/resources.ts",
 		"./vs/base/node/decoder.ts",
 		"./vs/base/node/id.ts",
 		"./vs/base/node/paths.ts",
@@ -313,4 +314,4 @@
 	"exclude": [
 		"./typings/require-monaco.d.ts"
 	]
-}
+}