repo-tools, create-app: replace duplicate error utilities with cli-common imports (#33893)

* Replace duplicate error utilities with @backstage/cli-common imports

Remove dead CustomError and ExitCodeError classes from repo-tools and
create-app, replacing them with the ExitCodeError import from
@backstage/cli-common. This fixes the instanceof check in exitWithError
so it actually catches errors thrown by cli-common's run().

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

* Add changeset for repo-tools and create-app

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

---------

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/replace-duplicate-error-utilities.md

@@ -0,0 +1,6 @@
+---
+'@backstage/repo-tools': patch
+'@backstage/create-app': patch
+---
+
+Replaced internal error utilities with shared ones from `@backstage/cli-common`.

packages/create-app/src/lib/errors.ts

@@ -14,27 +14,9 @@
  * limitations under the License.
  */
 
+import { ExitCodeError } from '@backstage/cli-common';
 import chalk from 'chalk';
 
-export class CustomError extends Error {
-  get name(): string {
-    return this.constructor.name;
-  }
-}
-
-export class ExitCodeError extends CustomError {
-  readonly code: number;
-
-  constructor(code: number, command?: string) {
-    if (command) {
-      super(`Command '${command}' exited with code ${code}`);
-    } else {
-      super(`Child exited with code ${code}`);
-    }
-    this.code = code;
-  }
-}
-
 export function exitWithError(error: Error): never {
   if (error instanceof ExitCodeError) {
     process.stderr.write(`\n${chalk.red(error.message)}\n\n`);

packages/repo-tools/src/lib/errors.ts

@@ -14,27 +14,9 @@
  * limitations under the License.
  */
 
+import { ExitCodeError } from '@backstage/cli-common';
 import chalk from 'chalk';
 
-export class CustomError extends Error {
-  get name(): string {
-    return this.constructor.name;
-  }
-}
-
-export class ExitCodeError extends CustomError {
-  readonly code: number;
-
-  constructor(code: number, command?: string) {
-    super(
-      command
-        ? `Command '${command}' exited with code ${code}`
-        : `Child exited with code ${code}`,
-    );
-    this.code = code;
-  }
-}
-
 export function exitWithError(error: Error): never {
   if (error instanceof ExitCodeError) {
     process.stderr.write(`\n${chalk.red(error.message)}\n\n`);