Description

Fixes #5479

The rescue blocks in Datadog::Tracing::Distributed::Datadog#extract_tags and #inject_tags! implicitly return true (the return value of Logger#warn) instead of nil.

For extract_tags, this true is passed to extract_trace_id!, which calls .delete on it, raising:

NoMethodError: undefined method 'delete' for true

Root cause

In lib/datadog/tracing/distributed/datadog.rb lines 166-171, the rescue block's last expression is ::Datadog.logger.warn(...), which returns true in Ruby. This becomes the method's implicit return value.

The caller chain:

1. #extract (line 69): trace_distributed_tags = extract_tags(fetcher) → gets true
2. #extract (line 73): extract_trace_id!(trace_id, trace_distributed_tags) → passes true
3. #extract_trace_id! (line 117): tags.delete(...) → NoMethodError on true

Why existing tests didn't catch this

The spec for "with invalid tags" mocks Datadog.logger with expect(...).to receive(:warn), which returns nil from the mock instead of true from the real logger, masking the bug.

Changes

• Add explicit nil after logger.warn in rescue blocks of both extract_tags and inject_tags!
• Add regression test that exercises #extract with invalid tags without mocking the logger

Impact

In our production environment, this generates ~30,000+ error logs per day. Any application receiving requests with malformed x-datadog-tags headers hits this.

Change log entry
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