Improves description for a case when default target is undefined

(#4224, #4258)

Author: sergeibbb

src/commands/changeBranchMergeTarget.ts

@@ -100,7 +100,7 @@ export class ChangeBranchMergeTargetCommand extends QuickCommand {
 				placeholder: 'Pick a merge target branch',
 				filter: (branch: GitBranch) => branch.remote && branch.name !== state.branch,
 				resetTitle: 'Reset Merge Target',
-				resetDescription: `Reset to "${detectedMergeTarget}"`,
+				resetDescription: detectedMergeTarget ? `Reset to "${detectedMergeTarget}"` : '',
 			});
 			if (result === StepResultBreak) {
 				continue;

src/commands/quickCommand.steps.ts

@@ -823,7 +823,7 @@ export function* pickOrResetBranchStep<
 
 	const resetButton: QuickInputButton = {
 		iconPath: new ThemeIcon('notebook-revert'),
-		tooltip: resetDescription,
+		tooltip: resetDescription || resetTitle,
 	};
 	let resetButtonClicked = false;
 	const step = createPickStep<BranchQuickPickItem>({