Figure out what's wrong with path parsing

[arduano]

These 2 test cases:

        assert_eq!(
            eval_ok("builtins.baseNameOf /foo/bar/baz/"),
            Value::Str("baz".into())
        );
        assert_eq!(
            eval_ok("(builtins.baseNameOf (/foo/bar/baz/))"),
            Value::Str("baz".into())
        );

Produce some very weird/unexpected results, including a panic on the second one.

[arduano]

In theory, paths cant have trailing slashes in the first place, and it should throw a parser error there instead.