Refactor

app/message-banner.tsx

@@ -0,0 +1,24 @@
+import {Action, actionClosedMessageBanner} from "./state/action.ts";
+import styles from "./message-banner.module.css";
+import {State} from "./state/state.ts";
+import {ActionDispatch} from "react";
+
+export default function MessageBanner({state, dispatch}:
+                                      {
+                                          state: State;
+                                          dispatch: ActionDispatch<[Action]>
+                                      }) {
+    function handleClose() {
+        dispatch(actionClosedMessageBanner());
+    }
+
+    if (!!state.errorMessage) {
+        return (
+            <div className={styles.banner + " " + styles.message}>
+                {state.errorMessage}
+                <button onClick={handleClose}>Dismiss message</button>
+            </div>
+        );
+    }
+    return (<div className={styles.banner + " " + styles.empty}></div>);
+}