[Ermine] Return nullSpec in quickui services

Change-Id: I3b43226a19cf269dc9c4ff70e5be7634a0e7f43f
diff --git a/session_shells/ermine/settings/lib/src/battery.dart b/session_shells/ermine/settings/lib/src/battery.dart
index ec06616..38f9c1b 100644
--- a/session_shells/ermine/settings/lib/src/battery.dart
+++ b/session_shells/ermine/settings/lib/src/battery.dart
@@ -47,7 +47,8 @@
 
   static Spec _specForBattery(double value, bool charging) {
     if (value.isNaN || value == 0) {
-      return null;
+      // Send nullSpec to hide battery settings.
+      return UiSpec.nullSpec;
     }
     final batteryText = '${value.toStringAsFixed(0)}%';
     if (value == 100) {
diff --git a/session_shells/ermine/settings/lib/src/bluetooth.dart b/session_shells/ermine/settings/lib/src/bluetooth.dart
index dc9aa3c..9d8b398 100644
--- a/session_shells/ermine/settings/lib/src/bluetooth.dart
+++ b/session_shells/ermine/settings/lib/src/bluetooth.dart
@@ -45,6 +45,10 @@
   }
 
   static Spec _specForBluetooth(List<TextValue> values) {
+    if (values.isEmpty) {
+      // No connected devices found. Send nullSpec to hide bluetooth settings
+      return UiSpec.nullSpec;
+    }
     return Spec(title: _title, groups: [
       Group(title: _title, values: [
         Value.withIcon(IconValue(codePoint: Icons.bluetooth.codePoint)),