The ModuleEntryTable::locked_create_entry_or_null() and PackageEntryTable::locked_create_entry_or_null() functions can be improved.

They unintuitively return null if the requested entry exists. In some cases, this is taken to mean the creation failed. In others, it is taken to mean that the entry already exists.

Additionally, PackageEntryTable::locked_create_entry_or_null() need not return a value.