FIX: handle argument error in api layer

lib/api/todos.rb

@@ -11,6 +11,10 @@ module API
       'issues' => ->(iid) { find_project_issue(iid) }
     }.freeze
 
+    rescue_from ArgumentError do |e|
+      render_api_error!(e.message, 400)
+    end
+
     params do
       requires :id, type: String, desc: 'The ID of a project'
     end

spec/requests/api/todos_spec.rb

@@ -34,6 +34,13 @@ RSpec.describe API::Todos do
     end
 
     context 'when authenticated' do
+      context 'when invalid params' do
+        it "returns argument error" do
+          get api('/todos', john_doe), params: { type: 'InvalidType' }
+          expect(response).to have_gitlab_http_status(:bad_request)
+        end
+      end
+
       it 'returns an array of pending todos for current user' do
         get api('/todos', john_doe)