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/context_menus/DialpadContextMenu.tsx

@@ -69,7 +69,7 @@ export default class DialpadContextMenu extends React.Component<IProps, IState>
         this.setState({ value: ev.target.value });
     };
 
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         return (
             <ContextMenu {...this.props}>
                 <div className="mx_DialPadContextMenuWrapper">

src/components/views/context_menus/GenericElementContextMenu.tsx

@@ -47,7 +47,7 @@ export default class GenericElementContextMenu extends React.Component<IProps> {
         }
     };
 
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         return <div>{this.props.element}</div>;
     }
 }

src/components/views/context_menus/GenericTextContextMenu.tsx

@@ -21,7 +21,7 @@ interface IProps {
 }
 
 export default class GenericTextContextMenu extends React.Component<IProps> {
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         return (
             <div className="mx_Tooltip mx_Tooltip_visible" style={{ display: "block" }}>
                 {this.props.message}

src/components/views/context_menus/LegacyCallContextMenu.tsx

@@ -46,7 +46,7 @@ export default class LegacyCallContextMenu extends React.Component<IProps> {
         this.props.onFinished();
     };
 
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         const holdUnholdCaption = this.props.call.isRemoteOnHold() ? _t("Resume") : _t("Hold");
         const handler = this.props.call.isRemoteOnHold() ? this.onUnholdClick : this.onHoldClick;
 

src/components/views/context_menus/MessageContextMenu.tsx

@@ -376,7 +376,7 @@ export default class MessageContextMenu extends React.Component<IProps, IState>
         this.closeMenu();
     };
 
-    public render(): JSX.Element {
+    public render(): React.ReactNode {
         const cli = MatrixClientPeg.get();
         const me = cli.getUserId();
         const { mxEvent, rightClick, link, eventTileOps, reactions, collapseReplyChain, ...other } = this.props;