_Panels: Added a placeholder panel

src/panels/_Panels.tsx

@@ -7,6 +7,7 @@ import React from "react";
 import FahrplanPanel from "./Fahrplan/FahrplanPanel";
 import {PanelDefinition} from "../types/LayoutConfig";
 import BildPanel from "./Bild";
+import PanelWrapper from "../meta/PanelWrapper";
 
 /*
  * First, please claim a unique id for your panel here. Convention is that it is all lowercase, in snake-case to be
@@ -22,7 +23,12 @@ export type PanelTypes = "fahrplan" | "bild";
  */
 export const PanelRenderers: {[panelType: string]: React.FC<any & {definition: PanelDefinition<any>}>} = {
   "fahrplan": FahrplanPanel,
-  "bild": BildPanel
+  "bild": BildPanel,
+  "placeholder": () => (
+    <PanelWrapper className={"flex flex-col items-center justify-center text-zinc-400"}>
+      Dieses Panel wird noch entwickelt
+    </PanelWrapper>
+  )
 };