fix(portal): Catch seat limit error in API fallback controller (#7783)

Why:

* The fallback controller in the API was not catching `{:error,
:seat_limit_reached}` being returned and was then generating a 500
response when this happened. This commit adds the condition in the
fallback controller and adds a new template for a more specific error
message in the returned JSON.

elixir/apps/api/lib/api/controllers/error_json.ex

@@ -1,4 +1,8 @@
 defmodule API.ErrorJSON do
+  def render(_template, %{reason: reason} = _assigns) do
+    %{error: %{reason: reason}}
+  end
+
   def render(template, _assigns) do
     %{error: %{reason: Phoenix.Controller.status_message_from_template(template)}}
   end

elixir/apps/api/lib/api/controllers/fallback_controller.ex

@@ -29,6 +29,20 @@ defmodule API.FallbackController do
     |> render(:"422")
   end
 
+  def call(conn, {:error, :seats_limit_reached}) do
+    conn
+    |> put_status(:unprocessable_entity)
+    |> put_view(json: API.ErrorJSON)
+    |> render(:error, reason: "Seat Limit Reached")
+  end
+
+  def call(conn, {:error, :service_accounts_limit_reached}) do
+    conn
+    |> put_status(:unprocessable_entity)
+    |> put_view(json: API.ErrorJSON)
+    |> render(:error, reason: "Service Accounts Limit Reached")
+  end
+
   def call(conn, {:error, %Ecto.Changeset{} = changeset}) do
     conn
     |> put_status(:unprocessable_entity)

elixir/apps/api/test/api/controllers/actor_controller_test.exs

@@ -145,6 +145,58 @@ defmodule API.ActorControllerTest do
                }
     end
 
+    test "returns error when user seat limit hit", %{
+      conn: conn,
+      account: account,
+      actor: api_actor
+    } do
+      Domain.Accounts.update_account(account, %{
+        limits: %{users_count: 1}
+      })
+
+      Fixtures.Actors.create_actor(type: :account_user, account: account)
+
+      attrs = %{
+        "name" => "Test User",
+        "type" => "account_user"
+      }
+
+      conn =
+        conn
+        |> authorize_conn(api_actor)
+        |> put_req_header("content-type", "application/json")
+        |> post("/actors", actor: attrs)
+
+      assert resp = json_response(conn, 422)
+      assert resp == %{"error" => %{"reason" => "Seat Limit Reached"}}
+    end
+
+    test "returns error when service account seat limit hit", %{
+      conn: conn,
+      account: account,
+      actor: api_actor
+    } do
+      Domain.Accounts.update_account(account, %{
+        limits: %{service_accounts_count: 1}
+      })
+
+      Fixtures.Actors.create_actor(type: :service_account, account: account)
+
+      attrs = %{
+        "name" => "Test Service Account",
+        "type" => "service_account"
+      }
+
+      conn =
+        conn
+        |> authorize_conn(api_actor)
+        |> put_req_header("content-type", "application/json")
+        |> post("/actors", actor: attrs)
+
+      assert resp = json_response(conn, 422)
+      assert resp == %{"error" => %{"reason" => "Service Accounts Limit Reached"}}
+    end
+
     test "creates a actor with valid attrs", %{conn: conn, actor: api_actor} do
       # TODO: At the moment, API clients aren't allowed to create admin users
       attrs = %{