fix(codewhisperer): empty suggestion UI notification not shown (#4563)

* fix empty response UI prompt not being shown

* changelog

* fix linter error irrelated to this PR

* Update .changes/next-release/Bug Fix-123af990-5e29-4d3a-aa38-63676e0b215c.json

---------

Co-authored-by: Justin M. Keyes <[email protected]>

Author: Will-ShaoHua

.changes/next-release/Bug Fix-123af990-5e29-4d3a-aa38-63676e0b215c.json

@@ -0,0 +1,4 @@
+{
+	"type": "Bug Fix",
+	"description": "CodeWhisperer: UI notification \"no suggestion\" not shown correctly"
+}

packages/core/src/codewhisperer/service/inlineCompletionService.ts

@@ -137,6 +137,9 @@ export class InlineCompletionService {
                 if (RecommendationHandler.instance.checkAndResetCancellationTokens()) {
                     RecommendationHandler.instance.reportUserDecisions(-1)
                     await vscode.commands.executeCommand('aws.codeWhisperer.refreshStatusBar')
+                    if (triggerType === 'OnDemand' && session.recommendations.length === 0) {
+                        void showTimedMessage(response.errorMessage ? response.errorMessage : noSuggestions, 2000)
+                    }
                     return {
                         result: 'Failed',
                         errorMessage: 'cancelled',