cmake "include()" statement does not (always) error out when the target file does not exist?

I just spent two hours of debugging until I found an interesting problem. In my package-configuration, I write


Through a copy-paste-error, the variable MY_PROJECT_NAME was not defined, so the code resolved to


This did not trigger an error with cmake, even though I understand such a file should not exist. Is it possible that the include() statement falls through missing files without error? That seems horrible. Or am I on the wrong track here?

include() definitely at least makes noise when files don’t exist (though I remember it being an error). I think it is “just” a SEND_ERROR though and so doesn’t stop processing right away. Is there, perhaps, actually a Targets.cmake file there from other copy/paste errors?