If an exception occurs during a module's _add_instance function, this
results in a course_modules entry with instance=0. The system already
handled returning false to this function, but did not handle
exceptions.
- changed the place where module file is included to make sure that add_moduleinfo() can be called independently from create_module()
- removed permission check from add_moduleinfo() because this function is not supposed to check permissions. Besides it's only half-check. See can_add_moduleinfo()
- added phpdocs to some functions to indicate that they can throw an exception
Simey Lameze