Inaccurate errors message during conversion status
I think this issue will be resolved by #292 (closed) and #310 (closed).
To confirm expected behaviour: When a chapter or book is being processed (i.e. has status Converting or Loading Preview) there should be no errors visible unless the user selects "Show history"
[original issues]
As files are converting, user should probably not be about to go to Error tab for those files.
Right now, even if a file has not converted yet (user was working on ch01.doc), if they go to the error tab they see a message that says: "Errors in ch01.doc(V1) on 2020-12-08 12:00:46", but there are no errors in the table below.
Or if they can go to Errors tab, they should at least have an accurate message, such as "No errors yet, file processing is in progress"
