Avoid using app.createEventEmitter

extensions/ql-vscode/src/queries-panel/query-discovery.ts

@@ -3,6 +3,7 @@ import { Discovery } from "../common/discovery";
 import { CodeQLCliServer } from "../codeql-cli/cli";
 import {
   Event,
+  EventEmitter,
   RelativePattern,
   Uri,
   WorkspaceFolder,
@@ -53,7 +54,7 @@ export class QueryDiscovery
   ) {
     super("Query Discovery", extLogger);
 
-    this.onDidChangeQueriesEmitter = this.push(app.createEventEmitter<void>());
+    this.onDidChangeQueriesEmitter = this.push(new EventEmitter<void>());
     this.push(workspace.onDidChangeWorkspaceFolders(this.refresh.bind(this)));
     this.push(this.watcher.onDidChange(this.refresh.bind(this)));
   }

extensions/ql-vscode/test/vscode-tests/minimal-workspace/queries-panel/query-discovery.test.ts

@@ -153,12 +153,7 @@ describe("QueryDiscovery", () => {
           .mockResolvedValue([join(workspaceRoot, "query1.ql")]),
       });
 
-      const discovery = new QueryDiscovery(
-        createMockApp({
-          createEventEmitter: () => new EventEmitter(),
-        }),
-        cli,
-      );
+      const discovery = new QueryDiscovery(createMockApp({}), cli);
 
       const onDidChangeQueriesSpy = jest.fn();
       discovery.onDidChangeQueries(onDidChangeQueriesSpy);
@@ -185,9 +180,7 @@ describe("QueryDiscovery", () => {
         .mockImplementation(onDidChangeWorkspaceFoldersEvent.event);
 
       const discovery = new QueryDiscovery(
-        createMockApp({
-          createEventEmitter: () => new EventEmitter(),
-        }),
+        createMockApp({}),
         mockedObject<CodeQLCliServer>({
           resolveQueries: jest.fn().mockResolvedValue([]),
         }),