v2.0.x Chore - Consider: Standardize error handling approach.

[reactive-firewall]

Standardize error handling approach.

While the error handling is thorough, there are inconsistencies in the approach:

Error variable naming varies (ImportErr vs _cause)
Some errors are explicitly cleaned up while others aren't
Consider standardizing the approach:

 try:
 	try:
 		import context
-	except Exception as ImportErr:  # pragma: no branch
-		ImportErr = None
-		del ImportErr  # skipcq - cleanup any error leaks early
+	except Exception as _cause:  # pragma: no branch
+		del _cause  # skipcq - cleanup any error leaks early
 		from . import context
 	if context.__name__ is None:
 		raise ImportError("[CWE-758] Failed to import context") from None
 	else:
 		from context import sys
 		from context import os
 		from context import unittest
-except Exception as _cause:  # pragma: no branch
-	raise ImportError("[CWE-758] Failed to import test context") from _cause
+except Exception as baton:  # pragma: no branch
+	raise ImportError("[CWE-758] Failed to import test context") from baton

1. name caught exceptions _cause or _root_cause when handled
   • _causes should not be documented in the docstrings; handler behavior may be documented on a case by case basis
   • _causes should be preemptively cleaned up
   • _causes may be chained, instead of cleaned up, when raising exceptions caused by _cause
   • _root_causes may be used in nested try-catch to avoid name shadowing _causes
2. name caught exceptions baton when chaining errors
   • batons should be documented in the docstrings
   • batons should never be preemptively cleaned up