fix: avoid mutable default in InfinityError headers

[dajiaohuang]

Description

Fixes #38909 - InfinityError uses a mutable default argument for headers, shared across all instances.

Changes

• Changed default from to to match the convention used by , , and .
• This prevents the bug where all instances without explicit headers share the same mutable dictionary.

Testing

The issue reporter provided a reproduction case:

[CLAassistant]

All committers have signed the CLA.

[greptile-apps]

Greptile Summary

Updates InfinityError to avoid sharing a mutable default dictionary between instances.

• Changes the optional headers default from {} to None.
• Aligns the constructor with the shared base exception and sibling provider exception contracts.

Confidence Score: 5/5

The PR appears safe to merge with no actionable regressions identified.

The new default follows the established optional-header contract, while existing callers and downstream exception handling support None without changing explicit-header behavior.

Important Files Changed

Filename	Overview
litellm/llms/infinity/common_utils.py	Safely replaces the mutable headers default with None; the base exception accepts it and downstream handling normalizes absent headers.

_{Reviews (1): Last reviewed commit: "fix: InfinityError uses None default for..." | Re-trigger Greptile}

[codspeed]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

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_{Comparing dajiaohuang:fix/38909-infinity-error-mutable-default (20d5d60) with litellm_internal_staging (31ca4dd)}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[dajiaohuang]

Updated title to fix: avoid mutable default in InfinityError headers. The recorded OSV failure is baseline dependency exposure from pypdf 6.15.0 and tornado 6.5.7 in uv.lock (5 known vulnerabilities; no changed dependency files), so this PR does not introduce it.

[dajiaohuang]

Closing as superseded by #39303, which consolidates this InfinityError fix with the related mutable-default fixes.