Diagnostics: improve error surfacing and busy state handling

pikit-web/assets/diaglog.js

@@ -107,8 +107,8 @@ export async function initDiagUI({ elements, toast }) {
         const entries = await syncState();
         render(entries);
         toast?.("Diagnostics refreshed (after retry)", "success");
-      } catch {
-        // swallow
+      } catch (err2) {
+        toast?.(err2.error || "Diagnostics still failing", "error");
       }
     } finally {
       setBusy(false);
@@ -126,6 +126,8 @@ export async function initDiagUI({ elements, toast }) {
     } catch (e) {
       toast?.(e.error || "Failed to save diagnostics setting", "error");
       enableToggle.checked = !enableToggle.checked;
+      setBusy(false);
+      return;
     } finally {
       setBusy(false);
     }