Backend error when the pattern matches an empty substring

[zhenyavinogradov]

When you try to use a pattern which can match an empty substring, backend fails without responding to the query. E.g. searching for x?: https://hackage-search.serokell.io/?q=x%3F

In the logs there is this error: Cannot decode byte '\xc2': Data.Text.Internal.Encoding.decodeUtf8: Invalid UTF-8 stream. Maybe it's because decodeUtf8 is applied to a sliced bytestring, and the slice can happen in the middle of a UTF-8 sequence.

hackage-search/backend/Search.hs

Line 548 in 0e2ef73

slice n m = Text.decodeUtf8 (sliceByteString n m raw_str)