Hello and thanks for reporting this.
This is a minor warning that I was aware of. You would see this warning in your logs if you have no fiat coin adapters enabled. It is unlikely that you are encountering any real problems because of it. In any case, I have now fixed it in version 0.5.3-beta just to make sure. This version will be released later today.
If you are encountering any issues with plugin functionality, they are likely due to a different error. So please open a new thread and describe the error if it persists.
with regards