FIX: add email reply error message for topic not getting created in restricted category

spec/components/email/receiver_spec.rb

@@ -562,6 +562,25 @@ greatest show ever created. Everyone should watch it.
       expect(e.message).to include("too short")
     end
 
+
+    it "blocks user in restricted group from creating topic" do
+      to = "some@email.com"
+
+      restricted_user = Fabricate(:user, trust_level: 4)
+      restricted_group = Fabricate(:group)
+      restricted_group.add(restricted_user)
+      restricted_group.save
+
+      category = Fabricate(:category, email_in_allow_strangers: false, email_in: to)
+      category.set_permissions(restricted_group => :readonly)
+      category.save
+
+      expect{
+        process_email(from: restricted_user.email, to: to)
+      }.to raise_error(Discourse::InvalidAccess)
+    end
+
+
   end