fix: use error query param if set

[balazsorban44]

If a custom error page was defined, the error query param wasn't taken into account.

Fixes #3106

See #3106 for more context. I now have tested this locally with a custom error page.

[codecov-commenter]

Codecov Report

Merging #3141 (7c6c88b) into beta (f998bf2) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             beta    #3141      +/-   ##
==========================================
- Coverage   13.87%   13.86%   -0.02%     
==========================================
  Files          86       86              
  Lines        1362     1363       +1     
  Branches      376      377       +1     
==========================================
  Hits          189      189              
- Misses       1162     1163       +1     
  Partials       11       11              

Impacted Files	Coverage Δ
src/next/index.ts	0.00% <0.00%> (ø)

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[github-actions]

🎉 Experimental release published on npm!

npm i next-auth@0.0.0-pr.3141.0a0bc030

yarn add next-auth@0.0.0-pr.3141.0a0bc030