I am where I usually am, but not always logged in here.
Not sure,… but you can switch off the validity check on save:
Window > Preferences > General
[ ]
Automatically check models for problems
[ ]
Automatically fix problems when they are found
###SketchUp User Guide
ADD: I’ve opened a thread on the lack of a SketchUp Help Center article for these types of errors:
The magnifying glass icon (at top right) is a forum search feature.
Searching on “validity check” will bring up a multitude of topic threads, like: