I think there are two possible ways to fix that.
1. Make the name a required parameter.
2. Provide a default value.
I choosed option 1 in this fix to be consistent with other .new functions.
Also I think `RNA_def_string` instead of `RNA_def_string_file_path` should be used here. Looks like a copy-paste error.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D3728
554b26cf88