Conform more of the code base to strict null checking (#10147)

* Conform more of the code base to strict null checking

* More strict fixes

* More strict work

* Fix missing optional type

* Iterate

src/components/views/auth/EmailField.tsx

@@ -74,7 +74,7 @@ class EmailField extends PureComponent<IProps> {
         return result;
     };
 
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         return (
             <Field
                 id={this.props.id}