fix: Sequence Matcher error in Bank Reconciliation

[marination]

Issue:

     File "/usr/lib64/python3.6/difflib.py", line 465, in get_matching_blocks
        if self.matching_blocks is not None:
    AttributeError: 'SequenceMatcher' object has no attribute 'matching_blocks'

• SequenceMatcher accepts two strings along with a junk value criteria
• If any of these input strings are None the error occurs. Empty strings work.

Fix:

• Make sure None inputs are replaced by empty strings