Fix bare except clauses and mutable default arguments

[Mr-Neutr0n]

Summary

• Replace bare except: with except Exception: in sqlite_database.py and mlsd/utils.py to avoid inadvertently catching KeyboardInterrupt and SystemExit, which can prevent graceful shutdowns and mask critical errors (PEP 8 E722).
• Replace mutable default arguments ([]) with None in imwatermark/vendor.py (set_by_bits and EmbedMaxDct.__init__) to prevent shared state between calls — a well-known Python pitfall where default mutable objects persist across invocations and can cause subtle bugs if modified in place.

Changes

invokeai/app/services/shared/sqlite/sqlite_database.py

• transaction() context manager: except: → except Exception:

invokeai/backend/image_util/mlsd/utils.py

• pred_squares(): three bare except: → except Exception: (lines 572, 578, 586)

invokeai/backend/image_util/imwatermark/vendor.py

• WatermarkEncoder.set_by_bits(bits=[]) → set_by_bits(bits=None) with None guard
• EmbedMaxDct.__init__(watermarks=[], ..., scales=[0, 36, 36], ...) → __init__(watermarks=None, ..., scales=None, ...) with None guards

Test plan

• Verify invokeai imports and starts without errors
• Verify MLSD control net processor works correctly
• Verify watermark encoding/decoding still functions as expected
• Verify database transactions commit and rollback correctly

[JPPhoto]

@Mr-Neutr0n Is there any way to add a test for this?

[Mr-Neutr0n]

added a test for this

[JPPhoto]

added a test for this

@Mr-Neutr0n Thanks. This PR is failing a python check. Once you address that, I'll be happy to review it.

[lstein]

@Mr-Neutr0n There are a couple of ruff errors showing up in the tests. Could you fix?

[lstein]

@JPPhoto I went ahead and fixed the failing python check. I did a bit of testing on database rollback and didn't encounter any problems, but I didn't test the watermarking and MLSD control net functionality.

[JPPhoto]

@lstein I think this is good. It doesn't solve the double ^C needed to exit Invoke but these changes make sense.