enable runtime checks for new lv projects in dev env (#5746)

See phoenixframework/phoenix_live_view#3161

installer/templates/phx_single/config/dev.exs

@@ -65,8 +65,11 @@ config :phoenix, :stacktrace_depth, 20
 # Initialize plugs at runtime for faster development compilation
 config :phoenix, :plug_init_mode, :runtime<%= if @html do %>
 
-# Include HEEx debug annotations as HTML comments in rendered markup
-config :phoenix_live_view, :debug_heex_annotations, true<% end %><%= if @mailer do %>
+config :phoenix_live_view,
+  # Include HEEx debug annotations as HTML comments in rendered markup
+  debug_heex_annotations: true,
+  # Enable helpful, but potentially expensive runtime checks
+  enable_expensive_runtime_checks: true<% end %><%= if @mailer do %>
 
 # Disable swoosh api client as it is only required for production adapters.
 config :swoosh, :api_client, false<% end %>

installer/templates/phx_umbrella/config/dev.exs

@@ -6,8 +6,11 @@ config :logger, :console, format: "[$level] $message\n"
 # Initialize plugs at runtime for faster development compilation
 config :phoenix, :plug_init_mode, :runtime<%= if @html do %>
 
-# Include HEEx debug annotations as HTML comments in rendered markup
-config :phoenix_live_view, :debug_heex_annotations, true<% end %><%= if @mailer do %>
+config :phoenix_live_view,
+  # Include HEEx debug annotations as HTML comments in rendered markup
+  debug_heex_annotations: true,
+  # Enable helpful, but potentially expensive runtime checks
+  enable_expensive_runtime_checks: true<% end %><%= if @mailer do %>
 
 # Disable swoosh api client as it is only required for production adapters.
 config :swoosh, :api_client, false<% end %>