Clarifies worktree create error handling

src/commands/git/stash.ts

@@ -294,6 +294,7 @@ export class StashGitCommand extends QuickCommand {
 			}
 
 			QuickCommand.endSteps(state);
+
 			try {
 				void (await state.repo.stashApply(
 					// pop can only take a stash index, e.g. `stash@{1}`
@@ -303,14 +304,12 @@ export class StashGitCommand extends QuickCommand {
 			} catch (ex) {
 				Logger.error(ex, context.title);
 
-				if (ex instanceof StashApplyError) {
-					if (ex.reason === StashApplyErrorReason.WorkingChanges) {
-						void window.showWarningMessage(
-							'Unable to apply stash. Your working tree changes would be overwritten. Please commit or stash your changes before trying again',
-						);
-					} else {
-						void Messages.showGenericErrorMessage(ex.message);
-					}
+				if (StashApplyError.is(ex, StashApplyErrorReason.WorkingChanges)) {
+					void window.showWarningMessage(
+						'Unable to apply stash. Your working tree changes would be overwritten. Please commit or stash your changes before trying again',
+					);
+				} else {
+					void Messages.showGenericErrorMessage(ex.message);
 				}
 			}
 		}

src/commands/git/worktree.ts

@@ -367,9 +367,8 @@ export class WorktreeGitCommand extends QuickCommand {
 				});
 			} catch (ex) {
 				if (
-					!state.flags.includes('--force') &&
-					ex instanceof WorktreeCreateError &&
-					ex.reason === WorktreeCreateErrorReason.AlreadyCheckedOut
+					WorktreeCreateError.is(ex, WorktreeCreateErrorReason.AlreadyCheckedOut) &&
+					!state.flags.includes('--force')
 				) {
 					const createBranch: MessageItem = { title: 'Create New Branch' };
 					const force: MessageItem = { title: 'Create Anyway' };
@@ -398,11 +397,11 @@ export class WorktreeGitCommand extends QuickCommand {
 						state.confirm = false;
 						continue;
 					}
-				} else if (ex instanceof WorktreeCreateError && ex.reason === WorktreeCreateErrorReason.AlreadyExists) {
-					void Messages.showGenericErrorMessage(
+				} else if (WorktreeCreateError.is(ex, WorktreeCreateErrorReason.AlreadyExists)) {
+					void window.showErrorMessage(
 						`Unable to create a new worktree in '${GitWorktree.getFriendlyPath(
 							uri,
-						)} because that folder already exists.`,
+						)} because that folder already exists and is not empty.`,
 					);
 				} else {
 					void Messages.showGenericErrorMessage(
@@ -610,7 +609,7 @@ export class WorktreeGitCommand extends QuickCommand {
 
 						await state.repo.deleteWorktree(uri, { force: force });
 					} catch (ex) {
-						if (ex instanceof WorktreeDeleteError) {
+						if (WorktreeDeleteError.is(ex)) {
 							if (ex.reason === WorktreeDeleteErrorReason.MainWorkingTree) {
 								void window.showErrorMessage('Unable to delete the main worktree');
 							} else if (!force) {

src/git/errors.ts

@@ -3,6 +3,10 @@ export const enum StashApplyErrorReason {
 }
 
 export class StashApplyError extends Error {
+	static is(ex: any, reason?: StashApplyErrorReason): ex is StashApplyError {
+		return ex instanceof StashApplyError && (reason == null || ex.reason === reason);
+	}
+
 	readonly original?: Error;
 	readonly reason: StashApplyErrorReason | undefined;
 
@@ -35,6 +39,10 @@ export const enum WorktreeCreateErrorReason {
 }
 
 export class WorktreeCreateError extends Error {
+	static is(ex: any, reason?: WorktreeCreateErrorReason): ex is WorktreeCreateError {
+		return ex instanceof WorktreeCreateError && (reason == null || ex.reason === reason);
+	}
+
 	readonly original?: Error;
 	readonly reason: WorktreeCreateErrorReason | undefined;
 
@@ -73,6 +81,10 @@ export const enum WorktreeDeleteErrorReason {
 }
 
 export class WorktreeDeleteError extends Error {
+	static is(ex: any, reason?: WorktreeDeleteErrorReason): ex is WorktreeDeleteError {
+		return ex instanceof WorktreeDeleteError && (reason == null || ex.reason === reason);
+	}
+
 	readonly original?: Error;
 	readonly reason: WorktreeDeleteErrorReason | undefined;