Javascript Calculator in React failing clear text

Tell us what’s happening:
My code is failing test #7 and #8 (which are worded exactly the same, which is bizarre in itself). The test failure does not provide me with any useful info:

Script error. (:0)
Error: Script error. (:0)
    at a.onerror (
    at Array.forEach (<anonymous>)
    at ae (
    at a.<anonymous> (
    at (
    at N.runTest (
    at o (

Your code so far

Your browser information:

User Agent is: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36.

Challenge: Build a JavaScript Calculator

Link to the challenge:

Line 60 this.evaluate(); - where is this function defined?

um, it wasn’t defined yet because I was working through the tests one by one. I guess I shouldn’t have written that or at least created a stub function because that fixed the issue, thanks!