escapePhrase(): Argument #1 ($input) must be of type string, array given

Could you provide a stack trace?

My problem seemed to be on custom code which calls createFilterQuery function.

Problem was that custom code had bug which allow send empty $value to createFilterQuery. When $value was empty and createFilterQuery will set $value be array then escapePhrase will gives error because code can allow $value be empty array and escapePhras expect $value be string then gives error.

I have resolved the issue & added patch, please review.

I don't think that the provided patch is right as it would hide other bugs.
An empty value has to be treated differently.

As also explained in #3 and #6, this isn't a bug in the module. The error occurs if some custom code provides an invalid argument.
So it is better to throw an exception instead of silently converting into something else.

Looking good

Automatically closed - issue fixed for 2 weeks with no activity.