Qhelpgenerator endless loop with -c option

When running qhelpgenerator with the option -c, as discussed here: https://github.com/doxygen/doxygen/issues/9135#issuecomment-1046743453

qhelpgenerator version 6.1.2 and 6.2.2 enters an infinite loop with a very small test project.

Running with version 5.15.2, it works out of the box and finishes in less than a second.

A minimal reproducer can be found in the link above.
 

Also, could it be clarified what the option -c exactly does? It seems that in version 5, it only looks for files in the "files" section, but not in the "toc". Does it also check recursively for links inside the HTML files itself, or just those in the qhp index? Right now, it looks ambiguous:

Usage:

qhelpgenerator <help-project-file> [options]

  -o <compressed-file>   Generates a Qt compressed help
                         file called <compressed-file>.
                         If this option is not specified
                         a default name will be used.
  -c                     Checks whether all links in HTML files
                         point to files in this help project.
  -v                     Displays the version of 
                         qhelpgenerator.