Make drawer scrollview non-primary.

This prevents an exception when both the main view and drawer is
visible, if both views are scrollable. It does not seem to impact
behavior at all.

lib/app/views/main_drawer.dart

@@ -25,6 +25,7 @@ class MainPageDrawer extends ConsumerWidget {
 
     return Drawer(
       child: ListView(
+        primary: false, //Prevents conflict with the MainPage scroll view.
         children: [
           Padding(
             padding: const EdgeInsets.all(12.0),