dart create: Stop progress before exiting with error

Otherwise the progress gizmo just keeps spinning, and dartdev never exits.

Change-Id: I53aa04a214354f3a5b085fa9d7bb562131f8ab95
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403990
Commit-Queue: Sigurd Meldgaard <sigurdm@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>

pkg/dartdev/lib/src/commands/create.dart

@@ -130,9 +130,9 @@ class CreateCommand extends DartdevCommand {
           }
         },
       );
-      if (exitCode != 0) return exitCode;
       progress.finish(showTiming: true);
       log.stdout(buffer.toString().trimRight());
+      if (exitCode != 0) return exitCode;
     }
 
     log.stdout('');