json.parse fails on negative integers

[RisingSunStudios]

Hi,

Found a bug in the lexer where it will throw a SyntaxErrorException with the message 'unexpected token: "-"' when the data contains a negative number.

json.parse("{ \"foo\": -1 }}")

[marianolarre]

This is such a simple and ubiquitous use case. Not workign with negative numbers it is unusable in most cases