For those experiencing this issue when pulling out your S-Pen, you can just go to Settings > App Info > Search and select Air Command > Storage > Clear Cache/Data
once done it will not crash anymore.
Thank you, WolfeGG, for sharing the positive results & tips here to solve the S-Pen Air Command keeps stopping error messages as below:
Settings > App Info > Search and select Air Command > Storage > Clear Cache/Data
This solution hasn't worked for me, since there was 0 cache to clear. Even clearing all cache on the device didn't do anything to prevent air command from stopping.