Make completion check resilient again stale elements.

Author: toinehartman

rascal-vscode-extension/src/test/vscode-suite/utils.ts

@@ -557,9 +557,13 @@ export function printRascalOutputOnFailure(channel: 'Language Parametric Rascal'
 
 export async function expectCompletions(driver: WebDriver, editor: TextEditor, expectedLabels: string[]) {
     await driver.wait(async () => {
-        const completionMenu = new ContentAssist(editor);
-        const completions = await ignoreFails(completionMenu.getItems());
-        const labels: string[] = await Promise.all(completions!.map(c => c.getLabel()));
-        return labels === expectedLabels;
+        try {
+            const completionMenu = new ContentAssist(editor);
+            const completions = await completionMenu.getItems();
+            const labels = await Promise.all(completions.map(c => c.getLabel()));
+            return labels === expectedLabels;
+        } catch (e) {
+            return false;
+        }
     }, Delays.fast, `Completion items do not equal ${expectedLabels}`);
 }