Give a message when string is too short or wrong in the consistency tool

[NekoJonez]

Today I was working on cleaning up old translations and I noticed that for this string:
​https://translate.wordpress.org/projects/wp-plugins/erp/stable/nl/default/?filters%5Bstatus%5D=either&filters%5Boriginal_id%5D=12800889&filters%5Btranslation_id%5D=89776558

There were strange other translations in the translation memory, so I went to the consistency tool to check where they came from... But, when I entered the short "0" string, nothing happened.

I think it would be a great QoL feature if there is some sort of message when the string is too short or generates some other error, since now it looks like the page just refreshes and nothing happened.

[vladytimy]

I think this is caused by evaluating 0 string value of $search to falsey on this line, hence it thinks there is no term to perform a search for.

if ( $search && $locale && $set_slug )
   $performed_search = true;

​Source file

It's an edge case but maybe the comparsion should be $search !== ''

[ocean90]

In 11345:

Translate, Consistency: Support searching for '0'.

Props vladytimy, ocean90.
Fixes #5966.