capture_backtrace raises AttributeError on PEP-420 namespace packages

[jacksmith15]

The new capture_backtrace function in scout_apm.core.backtrace raises an AttributeError when the stack includes a PEP-420 namespace package.

This is caused by the module_filepath function, specifically line 32:

    module_dir = sys.modules[root_module].__file__.rsplit(os.sep, 2)[0]

If sys.modules[root_module] is a PEP-420 namespace package, this will raise

AttributeError: 'NoneType' object has no attribute 'rsplit'

Steps to reproduce

Create a namespace package, with some modules inside, e.g.:

namespace/
    foo/
        __init__.py
    bar/
       __init__.py

Then on an interactive Python shell:

>>> from scout_apm.core.backtrace import module_filepath
>>> from namespace import foo
>>> module_filepath("namespace.foo", "namespace")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/jack/venvs/tmp-a17ac7185189989/lib/python3.8/site-packages/scout_apm/core/backtrace.py", line 32, in module_filepath
    module_dir = sys.modules[root_module].__file__.rsplit(os.sep, 2)[0]
AttributeError: 'NoneType' object has no attribute 'rsplit'

Details

• Tested with version 2.21.0
• Current workaround is to pin version to 2.20.0

[tim-schilling]

Hi Jack,

Thank you for the detailed issue. I'm looking into it.

-Tim

[tim-schilling]

@jacksmith15 Thank you for raising this. It will be fixed in v2.21.1 which is being released now. It'll be available within the hour.