Display a more user friendly message that this error. This happens when content is locked by another user or if the content is in live.
In addition, if the version is live or locked, it should default to preview mode, thereby avoiding the error altogether.
Thanks for another great idea.
We have added a ticket to update the error message to Asset '111111' has been locked by user 'tendenc'.
This is a fairly easy fix and we are hoping to have it ready as quickly as our next release.
We are still reviewing options for your second suggestion of opening a locked asset in preview mode which is a larger effort.