footway=* instead of sidewalk=* on roads

[Famlam]

​The key footway is quite often incorrectly used when (in most cases, most likely) sidewalk=* is meant.

Perhaps it is an idea to make the validator complain about "disallowed" highway values combined with footway=*? (Formally it's allowed on highway=footway/path/construction only, although it seems quite a common tag to use on highway=cycleway too)
​overpass-turbo for the area around The Netherlands

If not, then it might be worth adding a check for footway=* without highway=* tag (or prefixed highway keys)? ​Overpass-turbo