PropType error from _error.js on no error pages

[khrome83]

So I am using the error page example from the Readme.md.

I added propTypes to follow our ESLint standards. When loading / I get the follow error. When loading /page-does-not-exist I get no error. The issue is that React.propTypes is not found so string can not be resolved, yet I am importing React in the error file (like the example).

I would expect to get this issue when loading a error page, instead it shows for all files. Advice?

Uncaught TypeError: Cannot read property 'string' of undefined
    at Object.eval (eval at evalScript (eval-script.js?6d7f685:22), <anonymous>:90:40)
    at Object.581 (eval at evalScript (eval-script.js?6d7f685:22), <anonymous>:117:30)
    at __webpack_require__ (bootstrap 7a5f342…?09b487d:693)
    at fn (bootstrap 7a5f342…?09b487d:110)
    at Object.582 (eval at evalScript (eval-script.js?6d7f685:22), <anonymous>:125:18)
    at __webpack_require__ (bootstrap 7a5f342…?09b487d:693)
    at webpackJsonpCallback (bootstrap 7a5f342…?09b487d:23)
    at eval (eval at evalScript (eval-script.js?6d7f685:22), <anonymous>:2:1)
    at evalScript (eval-script.js?6d7f685:22)
    at Object.<anonymous> (next-dev.js?804dbaf:20)

[khrome83]

NM. Type-o that eslint plugin did not catch. Will file bug with them.