Use hooks for context

client/state/reactContext.tsx

@@ -33,20 +33,16 @@ export function ConsumeState({ children }: ConsumeStateProps) {
 
 export function injectState<P extends { appState: AppState }>(
   Component: React.ComponentType<P>
-): React.ComponentClass<Omit<P, "appState">> {
-  return class extends React.Component<Omit<P, "appState">> {
-    render() {
-      const consumeState = (state: AppState | null) => {
+): React.FunctionComponent<Omit<P, "appState">> {
+  return function InjectState(props) {
+    const state = React.useContext(StateContext);
     if (state == null) {
       throw new Error(
         "Component with injectState must be mounted inside ProvideState"
       );
     }
     // tslint:disable-next-line: no-object-literal-type-assertion
-        const allProps: Readonly<P> = {...this.props, appState: state} as Readonly<P>;
+    const allProps: Readonly<P> = {...props, appState: state} as Readonly<P>;
     return <Component {...allProps} />;
-      };
-      return <StateContext.Consumer>{consumeState}</StateContext.Consumer>;
   }
-  };
 }