[Bug]: PR #9902 considers all industry tile layouts of only one tile to be invalid

[JGRennison]

Version of OpenTTD

Since #9902

Expected result

Valid industry tile layouts which contain only one tile are not considered invalid

Actual result

Valid industry tile layouts which contain only one tile are considered invalid

The logic for counting the number of valid regular tiles in the industry tile layout is not correct, it should be done separately from the duplicate tile coordinate check.

Steps to reproduce

See a NewGRF industry set which defines industries with a tile layout containing only one tile (i.e 1x1 overall size), e.g. https://github.com/2TallTyler/plaza_ind