fix: editor buffer out of sync with file on disk

In #476 it was
incorrectly assumed that the content on disk is the most up-to-date
version. An unsaved buffer in the editor could be newer than the file on
disk and thus we should always load the script with the snapshot from
editor.

PR fix #632

Author: Keen Yee Liau

server/src/session.ts

@@ -166,19 +166,17 @@ export class Session {
   }
 
   private onDidOpenTextDocument(params: lsp.DidOpenTextDocumentParams) {
-    const {uri, languageId} = params.textDocument;
+    const {uri, languageId, text} = params.textDocument;
     const filePath = uriToFilePath(uri);
     if (!filePath) {
       return;
     }
     const scriptKind = languageId === LanguageId.TS ? ts.ScriptKind.TS : ts.ScriptKind.External;
-    // Since we are only keeping track of changes of files that are already on
-    // disk (see documentSelector.scheme in extension.ts), the content on disk
-    // is up-to-date when a file is first opened in the editor.
-    // In this case, we should not pass fileContent to projectService.
-    const fileContent = undefined;
     try {
-      const result = this.projectService.openClientFile(filePath, fileContent, scriptKind);
+      // The content could be newer than that on disk. This could be due to
+      // buffer in the user's editor which has not been saved to disk.
+      // See https://github.com/angular/vscode-ng-language-service/issues/632
+      const result = this.projectService.openClientFile(filePath, text, scriptKind);
 
       const {configFileName, configFileErrors} = result;
       if (configFileErrors && configFileErrors.length) {