Clearer error messages

[Guybrush88]

as reported by DostKaplan on the wall:

I inadvertantly typed in a hyphen (-) instead of the equals sign (=) in my search string:

-personally (instead of =personally)

The URL is: https://tatoeba.org/en/sentence...sonally&to=tur

Obviously this means I wouldn't expect to get any results because a search string like "-personally" is effectively equivalent to searching for an empty string. Instead of getting a more user-friendly, explanatory message, I got:

An error occurred while performing the search. If the problem persists, please let us know and include the error code "65fb71bbcc781" in your message.

I suggest showing the user a more meaningful message including a link to the Tatoeba-specific regexp help page.

https://tatoeba.org/it/wall/show_message/40565#!#message_40565