Break string for loop when the parser is erroring

src_v2/parser/parser_internals.nim

@@ -108,6 +108,7 @@ proc str*(expectedString: string): parserFnT {.inline.} =
   return proc(parser: Parser): ParserResult =
     var res: ParserResult = parser.ok()
     for c in expectedString.items:
+      if res.isErr: break
       res = res.flatMap(ch(c))
     return res