Hello,
I have tried to add some guard clauses in version 2.0.1. Hopefully this resolves your issue.
It looks like you were listing the markets in the admin screens, but a reference from a market to a (base or quote) currency was no longer available. Possibly a currency was deleted. The plugin can now handle this situation without crashing.
If the issue is not resolved, please let me know what you were trying to do when you saw the error, and whether you were on multisite.
with regards