Refrain creating ember-loose virtual code in non ember-loose environment

packages/core/src/volar/ember-language-plugin.ts

@@ -15,6 +15,7 @@ export type TS = typeof ts;
 export function createEmberLanguagePlugin<T extends URI | string>(
   glintConfig: GlintConfig,
 ): LanguagePlugin<T> {
+  const hasEmberLoose = glintConfig.environment.names.indexOf('ember-loose') !== -1;
   return {
     /**
      * For files that are not opened in the IDE, the language ID will not be provided
@@ -43,6 +44,7 @@ export function createEmberLanguagePlugin<T extends URI | string>(
 
       // See: https://github.com/JetBrains/intellij-plugins/blob/11a9149e20f4d4ba2c1600da9f2b81ff88bd7c97/Angular/src/angular-service/src/index.ts#L31
       if (
+        hasEmberLoose &&
         languageId === 'typescript' &&
         !scriptIdStr.endsWith('.d.ts') &&
         scriptIdStr.indexOf('/node_modules/') < 0

packages/vscode/__fixtures__/template-imports-app-ts-plugin/src/file.ts

@@ -0,0 +1 @@
+export let greeting = 'hello';

packages/vscode/__fixtures__/template-imports-app-ts-plugin/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "extends": "../../../../tsconfig.compileroptions.json",
   "glint": {
-    "environment": ["ember-loose", "ember-template-imports"]
+    "environment": ["ember-template-imports"]
   },
   "compilerOptions": {
     "baseUrl": "."

packages/vscode/__tests__/ts-plugin-tests/smoketest-template-imports-ts-plugin.test.ts

@@ -55,6 +55,31 @@ describe('Smoke test: ETI Environment (TS Plugin Mode)', () => {
       ]);
     });
 
+    test.only('gives diagnostics for TypeScript file', async () => {
+      let scriptURI = Uri.file(`${rootDir}/src/file.ts`);
+      let scriptEditor = await window.showTextDocument(scriptURI, { viewColumn: ViewColumn.One });
+
+      await hackishlyWaitForTypescriptPluginToActivate(scriptEditor, scriptURI);
+
+      // Comment out a property in the script that's referenced in the template
+      await scriptEditor.edit((edit) => {
+        edit.delete(new Range(0, 0, 0, 7));
+      });
+
+      // Wait for the diagnostic to show up
+      await waitUntil(() => languages.getDiagnostics(scriptURI).length);
+
+      // Verify it's what we expect
+      expect(languages.getDiagnostics(scriptURI)).toMatchObject([
+        {
+          message: "'greeting' is declared but its value is never read.",
+          source: 'ts',
+          code: 6133,
+          range: new Range(new Position(0, 4), new Position(0, 12)),
+        },
+      ]);
+    });
+
     describe('codeactions args', () => {
       test('adds missing args from template into Args type', async () => {
         let scriptURI = Uri.file(`${rootDir}/src/Greeting.gts`);