In our experience it's just a case of closing and re-opening and seeing if it happens again. If it's still running into errors, make sure that you've performed these steps before running Grove:
1. Right click the GROVE zip file you downloaded
2. Use the archive utility to unzip the files.
3. Drag the GROVE app into your applications folder.
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There's also a chance that an old save from before 0.2 can lead to errors like the above. If all else fails, try starting a new game and playing through to see if you still run into these crashes.
Hope that helps :)
- RegalBuster