Where filter without operator part does not work with integer and boolean values

[VKTB]

Description:
Sending the following request:
http://{{datagateway-api}}/search-api/datasets/0-8401-1070-7?filter={"include": [{"relation": "files", "scope": {"where": {"size": 1}}}]}

returns 400 BAD REQUEST:

local variable 'value' referenced before assignment

This errors only when integer or boolean values are used, but works fine with string values.

Acceptance criteria:

• Where filter without operator part should work with integer and boolean values