setup: report panic errors to user

many issues occur with setup, all this does is tell the user something
bad happened and to check the logs. Might help with solving issues.
Also fixed some now invalid typescript.

ts/modules/common.ts

@@ -5,7 +5,7 @@ export function toDateString(date: Date): string {
     const t12 = document.getElementById("lang-12h") as HTMLInputElement;
     const t24 = document.getElementById("lang-24h") as HTMLInputElement;
     let args1 = {};
-    let args2 = {
+    let args2: Intl.DateTimeFormatOptions = {
         hour: "2-digit",
         minute: "2-digit"
     };