It is currently not possible to build the bundled version of spidermonkey 78 with the latest stable release of python - 3.10.
- python 3.3 moved the "abstract base classes" of the collections module to a new collections.abc module, and 3.10 removed the aliases that had been left in for backwards compatibility. (See also https://bugs.python.org/issue37324)
- There is also a changed function name affecting the version of virtualenv bundled with the spidermonkey source.
This particularly affects users where python 3.10 has been installed by their system's package manager (see version matrix).
This was mentioned on the forums by @Dizaka: https://wildfiregames.com/forum/topic/65901-christmas-testing-bundle/#comment-472056