Handle parentless popups

popup-app/components/IdpSelect.js

@@ -78,7 +78,9 @@ class IdpSelect extends React.Component {
     const { customIdp, enteringCustomIdp, error } = this.state
     return (
       <div>
-        <h1 className="center">Log in to {appName}</h1>
+        <h1 className="center">
+          Log in to <span className="app-name">{appName}</span>
+        </h1>
         {error && <Error error={error} />}
         <p className="copy-gentle center">Choose where you log in</p>
         {enteringCustomIdp ? (

popup-app/components/NoParent.js

@@ -0,0 +1,11 @@
+import React from 'react'
+
+const NoParent = ({ appName }) => (
+  <div>
+    This window was opened to log you in to{' '}
+    <span className="app-name">{appName}</span>, but that app is no longer open.
+    You can close this window.
+  </div>
+)
+
+export default NoParent

popup-app/index.css

@@ -61,3 +61,8 @@ h1 {
   display: flex;
   justify-content: flex-end;
 }
+
+.app-name {
+  text-decoration: underline;
+  font-weight: bold;
+}

popup-app/index.js

@@ -7,6 +7,7 @@ import { getData, updateStorage } from '../src/storage'
 
 import IdpCallback from './components/IdpCallback'
 import IdpSelect from './components/IdpSelect'
+import NoParent from './components/NoParent'
 
 import './index.css'
 
@@ -24,24 +25,29 @@ const idps = [
 ]
 
 findAppOrigin().then(appOrigin => {
-  ReactDOM.render(
-    window.location.hash ? (
+  const appName = process.env.APP_NAME
+
+  let element
+  if (!appOrigin) {
+    element = <NoParent appName={appName} />
+  } else if (window.location.hash) {
+    element = (
       <IdpCallback
         appOrigin={appOrigin}
         afterLoggedIn={() => setTimeout(window.close, 750)}
       />
-    ) : (
-      <IdpSelect
-        idps={idps}
-        appOrigin={appOrigin}
-        appName={process.env.APP_NAME}
-      />
-    ),
-    document.getElementById('app-container')
-  )
+    )
+  } else {
+    element = <IdpSelect idps={idps} appOrigin={appOrigin} appName={appName} />
+  }
+
+  ReactDOM.render(element, document.getElementById('app-container'))
 })
 
 async function findAppOrigin() {
+  if (!window.opener) {
+    return null
+  }
   let appOrigin = await getStoredAppOrigin()
   if (appOrigin) {
     return appOrigin