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?