Description of problem:
Each asset has Metadata tab with Version history, containing commits. This can be used to view previous versions of the asset.
If you happen to try that with a commit that deleted the asset, an editor is opened (which is a bit strange in this case), with no content, and an error pop-up appears ('File "" could not be found.').

This is a valid use-case and an issue because:
1. People are curious and will try this, knowing the commit deleted the file, just to see what happens.
2. If the file is deleted via git, not GUI, there might be a commit message that doesn't make it immediately clear and so a user wouldn't know not to view this version.
In both cases, it looks very bad at the very least.


Version-Release number of selected component (if applicable):
BPMS 6.0 ER4


Steps to Reproduce:
1. Create an asset - e.g. a DRL file, fill in some content and save.
2. Delete this asset.
3. Recreate this asset - same type, same name.
4. Go to Metadata tab and Version history, try viewing the (4th) commit/revision that deleted the file.


Actual results:
Opened editor and error pop-up.


Expected results:
No error pop-up - just a message/pop-up informing about the fact that the file is unavailable because this commit deleted the asset. Possibly also no other editor being opened.