fix (connectpage): edge case with 0 backend selected

public/assets/pages/connectpage/ctrl_form.js

@@ -211,4 +211,11 @@ export default async function(render) {
             );
         }),
     ));
+
+    // feature7: empty connection handling
+    effect(connections$.pipe(
+        rxjs.filter((conns) => conns.length === 0),
+        rxjs.mergeMap((a) => Promise.reject(new Error("no backend selected"))),
+        rxjs.catchError(ctrlError()),
+    ));
 }

public/assets/pages/connectpage/ctrl_form_state.js

@@ -3,7 +3,6 @@ import rxjs from "../../lib/rx.js";
 const currentBackend$ = new rxjs.ReplaySubject(1);
 
 export function setCurrentBackend(n) {
-    console.log("SET: ", n);
     currentBackend$.next(n);
 }