Feature summary (what you would like to be able to do and where):
I propose creating some kind of linter that would run on MediaWiki:Editcheck-config.json files. In, for example, TextMatch checks configurations it should validate that query is a list if "mode": "replace" is not set and it is an object if it is. It also can check if there are any deprecated parameters (like enabled, ignoreLeadSection) present.

Benefits (why should this be implemented?):
We on ruwiki ran twice into such bugs -- in first case query was an object but we forgot to add "mode": "replace", in the second case we didn't know enabled was a deprecated parameter.