If you experience a crash and then the error message "Error: Server Error" when trying to re-connect, please try deleting the latest save file. Unfortunately, this will re-roll some of your latest progress. However, it's the best solution at the time being.
We hope this issue will be fixed when we launch the Secrets of Gloomrot free expansion in May.
You can delete the latest save file by browsing your saves in the "Continue" screen, and selecting "go to directory"
The folder in which you have your saves will then open. Autosaves are named AutoSave_X, where X is the save number. Removing the highest number will remove the latest save and, likely, allow you to re-connect.