fix: Stricter query string parsing - no empty casts

Signed-off-by: Wolfgang Walther <walther@technowledgy.de>

CHANGELOG.md

@@ -29,7 +29,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
  - #2444, Removed `db-pool-timeout` option, because this was removed upstream in hasql-pool. - @robx
  - #2343, PATCH requests that don't affect any rows no longer return 404 - @wolfgangwalther
- - #2537, Stricter parsing of query string. Instead of silently ignoring, the parser now throws on invalid syntax like json paths for embeddings, hints for regular columns, etc. - @wolfgangwalther
+ - #2537, Stricter parsing of query string. Instead of silently ignoring, the parser now throws on invalid syntax like json paths for embeddings, hints for regular columns, empty casts, etc. - @wolfgangwalther
 
 ### Deprecated
 

src/PostgREST/ApiRequest/QueryParams.hs

@@ -494,13 +494,18 @@ pRelationSelect = lexeme $ try ( do
 -- Left (line 1, column 2):
 -- unexpected '!'
 -- expecting ")", "," or end of input
+--
+-- >>> P.parse pFieldSelect "" "name::"
+-- Left (line 1, column 7):
+-- unexpected end of input
+-- expecting letter or digit
 pFieldSelect :: Parser SelectItem
 pFieldSelect = lexeme $
   try (
     do
       alias <- optionMaybe ( try(pFieldName <* aliasSeparator) )
       fld <- pField
-      cast' <- optionMaybe (string "::" *> many pIdentifierChar)
+      cast' <- optionMaybe (string "::" *> many1 pIdentifierChar)
       pEnd
       return $ SelectField fld (toS <$> cast') alias
   )