Small behavior fix

app/src/main/java/eu/faircode/email/FragmentAnswer.java

@@ -234,7 +234,8 @@ public class FragmentAnswer extends FragmentBase {
                         }, null, context));
                 }
 
-                bottom_navigation.findViewById(R.id.action_delete).setVisibility(answer == null ? View.GONE : View.VISIBLE);
+                if (answer == null)
+                    bottom_navigation.getMenu().removeItem(R.id.action_delete);
 
                 if (ActivityAnswer.canAnswer(context))
                     cbExternal.setVisibility(View.VISIBLE);

app/src/main/java/eu/faircode/email/FragmentRule.java

@@ -1027,7 +1027,8 @@ public class FragmentRule extends FragmentBase {
                     Log.e(ex);
                 } finally {
                     grpReady.setVisibility(View.VISIBLE);
-                    bottom_navigation.findViewById(R.id.action_delete).setVisibility(id < 0 ? View.GONE : View.VISIBLE);
+                    if (id < 0)
+                        bottom_navigation.getMenu().removeItem(R.id.action_delete);
                     bottom_navigation.setVisibility(View.VISIBLE);
                 }
             }