Ambigous error messages

[wdanilo]

Hello! I've got parser and I've found out that sometimes we get strange error messages, like the following one:

 Parser:2:3: error: expected: "$", "*", "+", "-", "/", "<",
    "==", ">", "^", "in", accessor (.),
    ambiguous use of a left-associative operator,
    ambiguous use of a non-associative operator,
    ambiguous use of a right-associative operator, end of input,
    letter or digit, operator, space
 a; b 
  ^   

but I've got no minimal use case for this bug so far.

[ekmett]

If you can derive a reasonable test case I'd be happy to dig in further.