I was looking at the code and seems the developer tried to fix this issue by releasing version 0.29.2 of the plugin.
Can you do the following to make sure you're using the newest version?
Go to:
C:\\Users\YourUserName\AppData\Local\gog.com\galaxy\plugins\installed
Navigate to Steam and check manifest.json file to see which version you're currently using.

If it's version other than 0.29.2:
Restart the Client -> wait a minute or two -> Restart the Client -> Check if the issue with steam crashing is still there