Quick filters break with empty PP query filter

Reproduction steps:

Create a new Page Provider in Studio:
 - remove all clauses from "Query filter"
 - define a Quick filter e.g. "versions" with clause "ecm:isVersion = 1"

Create associated search form/results. Deploy. Create a new document, create a version of it. Invoke search form and search/filter to show new document. Toggle the "versions" quick filter:

Expected result: search results should change

Actual results: search results stay the same

Note: toggling the quick filter does submit a new API request with the quick filter in the payload, but the results are the same.

Workaround: add a dummy clause to the "Query filter" PP definition e.g.

ecm:primaryType != 'Undefined'

(here "Undefined" is just a random string that does not represent any defined Document Type)