Enhance response handling for number types

[celestial-rose]

This PR addresses a critical bug in the implementation that caused non-output when streaming responses from models like Llama4 that can return numeric chunks. The issue stemmed from an inadequate check on incoming stream chunks, which assumed all chunks would have a .length property, leading to errors with non-string data types.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 4e7ca23f6aa4107d372739e197272d0043e9b18a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
workers-ai-provider	Patch

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