unable to compare string to any operator symbol (as string)

[mirdhyn]

For example, following code fail with runtime error: index out of range :

expression, err := govaluate.NewEvaluableExpression("'foo' == '-'")
result, err := expression.Evaluate(nil)

Same thing with any of the operator symbols (-, +, /, * and %)

[Knetic]

Sorry for the bug!

Looks like I missed some TokenKind checks when the expression gets parsed out into stages, and didn't have any test cases which would catch it. f0224e3 should fix any of these panic cases where strings are misinterpreted.

[mirdhyn]

Your commit successfully fixed the issue.
Thank you very much, that was a very fast reaction!