fix(accept-header): reject out-of-range accept-language weights - #97878
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acceptLanguage now rejects non-finite or out-of-range q-values (for instance: q=2, q=-0.5, q=abc, q=NaN) with the existing Invalid accept-language header error, instead of silently treating them as q=1. Near-zero weight values like q=0.0001 now rank as low priority. Their true position.
In the current state a disfavoured language was being sorted to the top. This was wrong. RFC 9110 defines q-values as strictly 0-1, this fix brings the implementation into spec.
I added new tests at:
packages/next/src/server/accept-header.test.ts
covering 5 cases: