Certificate validation issue

Hi, I'm using certvalidator 0.11.1 to validate a certificate with a chain.

The validation fails in method verify_crl, with the following traceback:

File "/usr/local/lib/python3.8/site-packages/certvalidator/init.py", line 193, in validate_usage
self._validate_path()
File "/usr/local/lib/python3.8/site-packages/certvalidator/init.py", line 121, in _validate_path
validate_path(self._context, candidate_path)
File "/usr/local/lib/python3.8/site-packages/certvalidator/validate.py", line 50, in validate_path
return _validate_path(validation_context, path)
File "/usr/local/lib/python3.8/site-packages/certvalidator/validate.py", line 402, in _validate_path
verify_crl(
File "/usr/local/lib/python3.8/site-packages/certvalidator/validate.py", line 1243, in verify_crl
if isinstance(distribution_point['crl_issuer'], x509.GeneralNames):
TypeError: string indices must be integers

Apparently one is trying to index a string with a string ...

Attached goes a series of test certificates with a target certificate (sig.der) and its certification chain. I got the error when checking the validity of sig.der.
sig.zip

Start in certvalidator/validate.py at verify_crl, especially the reported line 1243, and reproduce the failure with sig.der and the attached certificate chain in sig.zip. Trace how the distribution point is represented before that access. Done means validating sig.der no longer raises the reported TypeError.