fix: Bug creating duplicate category leads to crash screen (#1577)

Co-authored-by: Tony Vincent Yesudas <tony.yesudas@raisenow.com>

test/system/categories_test.rb

@@ -0,0 +1,26 @@
+require "application_system_test_case"
+
+class CategoriesTest < ApplicationSystemTestCase
+  setup do
+    sign_in @user = users(:family_admin)
+  end
+
+  test "can create category" do
+    visit categories_url
+    click_link I18n.t("categories.new.new_category")
+    fill_in "Name", with: "My Shiny New Category"
+    click_button "Create Category"
+
+    visit categories_url
+    assert_text "My Shiny New Category"
+  end
+
+  test "trying to create a duplicate category fails" do
+    visit categories_url
+    click_link I18n.t("categories.new.new_category")
+    fill_in "Name", with: categories(:food_and_drink).name
+    click_button "Create Category"
+
+    assert_text "Name has already been taken"
+  end
+end