Fix getScriptSnapshot for file with empty content

.changeset/spicy-swans-work.md

@@ -0,0 +1,5 @@
+---
+"@typescript/vfs": patch
+---
+
+Fix getScriptSnapshot for file with empty content

packages/typescript-vfs/src/index.ts

@@ -671,7 +671,7 @@ export function createVirtualLanguageServiceHost(
     getScriptFileNames: () => fileNames.slice(),
     getScriptSnapshot: fileName => {
       const contents = sys.readFile(fileName)
-      if (contents && typeof contents === "string") {
+      if (typeof contents === "string") {
         return ts.ScriptSnapshot.fromString(contents)
       }
       return

packages/typescript-vfs/test/index.test.ts

@@ -245,3 +245,16 @@ it("moduleDetection options", async () => {
   program.emit()
   expect(fsMap.get("index.js")).toEqual(`define(["require", "exports"], function (require, exports) {\n    "use strict";\n    Object.defineProperty(exports, "__esModule", { value: true });\n    var foo = 'foo';\n});\n`)
 })
+
+it("update file content to empty string", () => {
+  const options: ts.CompilerOptions = {
+    target: ts.ScriptTarget.ES2020,
+  }
+  const fsMap = createDefaultMapFromNodeModules(options, ts)
+  fsMap.set("index.ts", "console.logx('')")
+  const system = createSystem(fsMap)
+  const env = createVirtualTypeScriptEnvironment(system, ["index.ts"], ts, options)
+  env.updateFile("index.ts", "")
+  const diagnostics = env.languageService.getSemanticDiagnostics("index.ts")
+  expect(diagnostics.length).toBe(0)
+})