Don't crash when email settings are invalid

Fixes: https://git.pleroma.social/pleroma/pleroma/-/issues/2606
Fixes: https://gitlab.com/soapbox-pub/soapbox/-/issues/4

test/pleroma/application_requirements_test.exs

@@ -35,13 +35,13 @@ defmodule Pleroma.ApplicationRequirementsTest do
     setup do: clear_config([:welcome])
     setup do: clear_config([Pleroma.Emails.Mailer])
 
-    test "raises if welcome email enabled but mail disabled" do
+    test "warns if welcome email enabled but mail disabled" do
       clear_config([:welcome, :email, :enabled], true)
       clear_config([Pleroma.Emails.Mailer, :enabled], false)
 
-      assert_raise Pleroma.ApplicationRequirements.VerifyError, "The mail disabled.", fn ->
-        capture_log(&Pleroma.ApplicationRequirements.verify!/0)
-      end
+      assert capture_log(fn ->
+               assert Pleroma.ApplicationRequirements.verify!() == :ok
+             end) =~ "Welcome emails will NOT be sent"
     end
   end
 
@@ -57,15 +57,13 @@ defmodule Pleroma.ApplicationRequirementsTest do
 
     setup do: clear_config([:instance, :account_activation_required])
 
-    test "raises if account confirmation is required but mailer isn't enable" do
+    test "warns if account confirmation is required but mailer isn't enabled" do
       clear_config([:instance, :account_activation_required], true)
       clear_config([Pleroma.Emails.Mailer, :enabled], false)
 
-      assert_raise Pleroma.ApplicationRequirements.VerifyError,
-                   "Account activation enabled, but Mailer is disabled. Cannot send confirmation emails.",
-                   fn ->
-                     capture_log(&Pleroma.ApplicationRequirements.verify!/0)
-                   end
+      assert capture_log(fn ->
+               assert Pleroma.ApplicationRequirements.verify!() == :ok
+             end) =~ "Users will NOT be able to confirm their accounts"
     end
 
     test "doesn't do anything if account confirmation is disabled" do

test/pleroma/user_test.exs

@@ -572,6 +572,24 @@ defmodule Pleroma.UserTest do
       )
     end
 
+    test "it fails gracefully with invalid email config" do
+      cng = User.register_changeset(%User{}, @full_user_data)
+
+      # Disable the mailer but enable all the things that want to send emails
+      clear_config([Pleroma.Emails.Mailer, :enabled], false)
+      clear_config([:instance, :account_activation_required], true)
+      clear_config([:instance, :account_approval_required], true)
+      clear_config([:welcome, :email, :enabled], true)
+      clear_config([:welcome, :email, :sender], "lain@lain.com")
+
+      # The user is still created
+      assert {:ok, %User{nickname: "nick"}} = User.register(cng)
+
+      # No emails are sent
+      ObanHelpers.perform_all()
+      refute_email_sent()
+    end
+
     test "it requires an email, name, nickname and password, bio is optional when account_activation_required is enabled" do
       clear_config([:instance, :account_activation_required], true)