Fix crash on saving endpoint (FFUF related only)

[psyray]

Fix #1006

I've added :

• a try except block to catch error on duplicate record returned by get_or_create in saving_endpoint method
• a check on endpoint existence in dir_file_fuzz method

Errors are logged to the console with the URL.

Tested and working

Now we need to find why there are duplicates endpoints in the db
But it's another issue

[psyray]

@AnonymousWP
Discussed with @ocervell, we must prevent empty endpoint return.
So I have reworked the fix to :

1. Check if endpoint exists
2. If exists, get only the first one
3. Not exists, create new

In both case an endpoint is returned.

[yogeshojha]

Approved

[AnonymousWP]

See open conversation.

[psyray]

See open conversation.

Done

[yogeshojha]

Looks good!