title: ReactJS | App not working on IOS and IE/Edge
body: <p>Version Edge: 
  Microsoft Edge 44.18362.449.0
  Microsoft EdgeHTML 18.18362</p>
  
  <p>Version IE:
  11.592.18362.0</p>
  
  <p>Hopefully we can get this sorted quick:</p>
  
  <p>My reactjs project after being built and deployed is working on chrome and firefox - on windows and android. However on IE, Edge and Safari (also chrome on IOS) I get a blank page with the following error:</p>
  
  <p>For IE:</p>
  
  <pre><code>TypeError: Unable to get property 'index' of undefined or null reference
     {
        [functions]: ,
        __proto__: { },
        description: "Unable to get property 'index' of undefined or null reference",
        message: "Unable to get property 'index' of undefined or null reference",
        name: "TypeError",
        number: -2146823281,
        stack: "TypeError: Unable to get property 'index' of undefined or null reference
     at value (https://xxxx/static/js/main.9016f2a2.chunk.js:1:2786)
     at Za (https://xxxx/static/js/2.97b2c280.chunk.js:2:331602)
     at Ja (https://xxxx/static/js/2.97b2c280.chunk.js:2:331451)
     at ju (https://xxxx/static/js/2.97b2c280.chunk.js:2:366905)
     at Nl (https://xxxx/static/js/2.97b2c280.chunk.js:2:351180)
     at Al (https://xxxx/static/js/2.97b2c280.chunk.js:2:351108)
     at wl (https://xxxx/static/js/2.97b2c280.chunk.js:2:348431)
     at gl (https://xxxx/static/js/2.97b2c280.chunk.js:2:345175)
     at oc (https://xxxx/static/js/2.97b2c280.chunk.js:2:373109)
     at Anonymous function (https://xxxx/static/js/2.97b2c280.chunk.js:2:374484)",
        Symbol()_6.wutlnu1cxkj: undefined,
        Symbol(react.async_mode)_y.wutlnu1cxkj: undefined,
        Symbol(react.concurrent_mode)_x.wutlnu1cxkj: undefined,
        Symbol(react.context)_o.wutlnu1cxkj: undefined,
        Symbol(react.element)_i.wutlnu1cxkj: undefined,
        Symbol(react.forward_ref)_p.wutlnu1cxkj: undefined,
        Symbol(react.fragment)_k.wutlnu1cxkj: undefined,
        Symbol(react.fundamental)_u.wutlnu1cxkj: undefined,
        Symbol(react.lazy)_t.wutlnu1cxkj: undefined,
        Symbol(react.memo)_s.wutlnu1cxkj: undefined,
        Symbol(react.portal)_j.wutlnu1cxkj: undefined,
        Symbol(react.profiler)_m.wutlnu1cxkj: undefined,
        Symbol(react.provider)_n.wutlnu1cxkj: undefined,
        Symbol(react.responder)_v.wutlnu1cxkj: undefined,
        Symbol(react.scope)_w.wutlnu1cxkj: undefined,
        Symbol(react.strict_mode)_l.wutlnu1cxkj: undefined,
        Symbol(react.suspense)_q.wutlnu1cxkj: undefined,
        Symbol(react.suspense_list)_r.wutlnu1cxkj: undefined
     }
  </code></pre>
  
  <p>Edge:</p>
  
  <pre><code>TypeError: Unable to get property 'index' of undefined or null reference
  
  SCRIPT5007: SCRIPT5007: Unable to get property 'index' of undefined or null reference
  </code></pre>
  
  <p><strong>Interesting fact on the side:</strong> Before removing my <em>Header</em> component import (to troubleshoot) this same message came but instead of <em>index</em> it said <em>header</em>. I have no component called index. Except the initiating index.js. Thus I am assuming reactjs has a fundamental issue in these browsers. I assume it has problems of getting the file structures react builds?</p>
  
  <p>I have tried polyfill and core-js/stable, both make no difference in the outcome.</p>
  
  <p>*Unfortunately I can't access any developer tools on my Ipad to get the console log of ios chrome and safari. I assume it's the same issue though.</p>