fix(streaming) Prevent console.error(undefined) (#3747) #6056

Job	Run time
Deno	16s
Checking if it's valid for JSR	13s
Bun	9s
Fastly Compute	1m 0s
AWS Lambda	1m 2s
Lambda@Edge	1m 1s
Main	2m 7s
Node.js v18.18.2	1m 5s
Node.js v20.x	1m 8s
Type & Bundle size Check on Main	1m 13s
Type & Bundle size Check on PR	0s
workerd	1m 9s
Node.js v22.x	1m 2s
Coverage	12s
	11m 37s

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