Fix mutable default argument in lora_base.py

[shunfeng8421]

Issue: Found mutable default arguments ([], {}) in lora_base.py and related files. This is a classic Python bug pattern.

Problem: Mutable default arguments are created once at function definition time, and shared across all calls. This can cause unexpected state leaks between function calls.

Suggested fix:

# Before (buggy):
def some_function(arg=[]):
    pass

# After (fixed):
def some_function(arg=None):
    if arg is None:
        arg = []
    pass

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This is a static analysis finding. There are multiple occurrences in this repository - please verify if these are actually reachable code paths.

Thanks for your work on diffusers and open source!

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This issue was generated by Code Health Auditor