Suppress error pop-up for watch expression evaluation

src/debugAdapter/goDebug.ts

@@ -26,7 +26,8 @@ import {
 	StackFrame,
 	StoppedEvent,
 	TerminatedEvent,
-	Thread
+	Thread,
+	ErrorDestination
 } from 'vscode-debugadapter';
 import { DebugProtocol } from 'vscode-debugprotocol';
 import {
@@ -1586,9 +1587,18 @@ export class GoDebugSession extends LoggingDebugSession {
 				log('EvaluateResponse');
 			},
 			(err) => {
+				let dest: ErrorDestination;
+				// No need to repeatedly show the error pop-up when expressions
+				// are continiously reevaluated in the Watch panel, which
+				// already displays errors.
+				if (args.context === 'watch') {
+					dest = null
+				} else {
+					dest = ErrorDestination.User
+				}
 				this.sendErrorResponse(response, 2009, 'Unable to eval expression: "{e}"', {
 					e: err.toString()
-				});
+				}, dest);
 			}
 		);
 	}