Fixes langfuse/langfuse#8619

Another approach would be passing the environment starting from the call to LangfuseGeneration in start_generation. Not sure which one is the best fix

Disclaimer: Experimental PR review

Greptile Summary

This PR fixes a bug where span wrappers were losing their environment context when no environment parameter was explicitly provided during span creation. The change implements a simple fallback mechanism in the Span constructor at line 111, changing from self._environment = environment to self._environment = environment or langfuse_client._environment.

The issue occurred because the Langfuse client stores its environment setting in the _environment attribute (as configured via constructor or environment variables like LANGFUSE_TRACING_ENVIRONMENT), but when creating spans in a trace hierarchy, this environment wasn't being automatically inherited by child spans unless explicitly passed down through all method calls.

This fix ensures that all spans within a trace maintain consistent environment settings by falling back to the client's configured environment when none is explicitly provided. This is critical for proper trace organization in Langfuse, as the environment field is used for categorizing and filtering traces in the UI. The solution is minimal and non-breaking - it only affects spans where no environment is explicitly set, maintaining backward compatibility while fixing the inheritance issue.

The change integrates well with the existing codebase architecture where the client acts as the central configuration holder, and spans should naturally inherit these settings unless overridden.

Confidence score: 5/5

• This PR is safe to merge with minimal risk as it's a simple fallback mechanism that doesn't change existing behavior
• Score reflects the straightforward nature of the fix and its alignment with expected inheritance patterns
• No files require special attention as the change is isolated and well-contained