fix: provide clear error when importing VerifiedRoutes instead of using

installer/lib/phx_new/project.ex

@@ -22,6 +22,7 @@ defmodule Phx.New.Project do
   def new(project_path, opts) do
     project_path = Path.expand(project_path)
     app = opts[:app] || Path.basename(project_path)
+
     app_mod = Module.concat([opts[:module] || Macro.camelize(app)])
 
     %Project{
@@ -79,7 +80,10 @@ defmodule Phx.New.Project do
 
   defp expand_path_with_bindings(path, %Project{} = project) do
     Regex.replace(Regex.recompile!(~r/:[a-zA-Z0-9_]+/), path, fn ":" <> key, _ ->
-      project |> Map.fetch!(:"#{key}") |> to_string()
+      case Map.fetch(project, :"#{key}") do
+        {:ok, value} -> to_string(value)
+        :error -> ":#{key}"
+      end
     end)
   end
 end

lib/phoenix/verified_routes.ex

@@ -927,6 +927,18 @@ defmodule Phoenix.VerifiedRoutes do
   defp build_route(route_ast, sigil_p, env, endpoint_ctx, router) do
     config = Module.get_attribute(env.module, :phoenix_verified_config, [])
 
+    if config == [] do
+      raise ArgumentError, """
+      attempted to use Phoenix.VerifiedRoutes without calling `use Phoenix.VerifiedRoutes` first.
+
+      You must use `use Phoenix.VerifiedRoutes` with the appropriate options instead of importing it:
+
+          use Phoenix.VerifiedRoutes, endpoint: MyAppWeb.Endpoint, router: MyAppWeb.Router
+
+      See the documentation for more details on configuration options.
+      """
+    end
+
     router =
       case Macro.expand(router, env) do
         mod when is_atom(mod) ->