Expanded Issue Transfer Error Messaging

Rather than discarding the error message when
the issue transfer fails, we should give it in the
console so that the user can correct it.

tools/monorepo-merge/src/commands/transfer-issues/index.ts

@@ -447,7 +447,12 @@ export default class TransferIssues extends Command {
 
 			return transferIssue.issue.id;
 		} catch ( err ) {
-			CliUx.ux.action.stop( 'Failed to migrate issue' );
+			if ( err instanceof GraphqlResponseError && err.errors ) {
+				CliUx.ux.action.stop( err.errors[0].message );
+			} else {
+				CliUx.ux.action.stop( 'Failed to migrate issue' );
+			}
+
 			return null;
 		} finally {
 			CliUx.ux.action.stop();