debug: no aria alert if start line number after last line

src/vs/workbench/contrib/debug/browser/debugService.ts

@@ -794,8 +794,11 @@ export class DebugService implements IDebugService {
 				if (editor) {
 					const control = editor.getControl();
 					if (stackFrame && isCodeEditor(control) && control.hasModel()) {
-						const lineContent = control.getModel().getLineContent(stackFrame.range.startLineNumber);
-						aria.alert(nls.localize('debuggingPaused', "Debugging paused {0}, {1} {2} {3}", thread && thread.stoppedDetails ? `, reason ${thread.stoppedDetails.reason}` : '', stackFrame.source ? stackFrame.source.name : '', stackFrame.range.startLineNumber, lineContent));
+						const model = control.getModel();
+						if (stackFrame.range.startLineNumber <= model.getLineCount()) {
+							const lineContent = control.getModel().getLineContent(stackFrame.range.startLineNumber);
+							aria.alert(nls.localize('debuggingPaused', "Debugging paused {0}, {1} {2} {3}", thread && thread.stoppedDetails ? `, reason ${thread.stoppedDetails.reason}` : '', stackFrame.source ? stackFrame.source.name : '', stackFrame.range.startLineNumber, lineContent));
+						}
 					}
 				}
 			});