chore: remove stacktrace from new message

lib/mix/task.ex

@@ -235,14 +235,16 @@ defmodule Igniter.Mix.Task do
                   if last && String.ends_with?(last, ",") do
                     arg_name = String.replace(to_string(k), "_", "-")
 
-                    raise """
+                    Mix.shell().error("""
                     Found trailing comma in `--#{arg_name}` at `#{last}`
 
                     Please remove the trailing comma.
 
                     On some platforms, argument parsing requires quotes around argument values containing commas.
                     So instead of `--#{arg_name} foo,bar`, you may need `--#{arg_name} "foo,bar"`
-                    """
+                    """)
+
+                    exit({:shutdown, 1})
                   end
                 end)
                 |> Enum.flat_map(&String.split(&1, ",", trim: true))