ArgumentError :erlang.binary_to_existing_atom/2
errors were found at the given arguments: * 1st argument: not an already existing atom

lib/fun_with_flags/ui/router.ex in anonymous fn/3 in FunWithFlags.UI.Router.do_match/4 at line 99
lib/plug/router.ex in anonymous fn/4 in FunWithFlags.UI.Router.dispatch/2 at line 246
/opt/app/deps/telemetry/src/telemetry.erl in :telemetry.span/3 at line 321
lib/plug/router.ex in FunWithFlags.UI.Router.dispatch/2 at line 242
lib/fun_with_flags/ui/router.ex in FunWithFlags.UI.Router.plug_builder_call/2 at line 1
lib/phoenix/router/route.ex in Phoenix.Router.Route.call/2 at line 42
lib/phoenix/router.ex in Phoenix.Router.__call__/5 at line 425

defmodule FunWithFlags.UI.Router do
  ...
  get "/flags/:name" do
    case Utils.get_flag(name) do
      ...
    end
  end
  ...
end

defmodule FunWithFlags.UI.Utils do
  ...
  def get_flag(name) do
    ..
    case FunWithFlags.SimpleStore.lookup(String.to_existing_atom(name)) do
      ...
    end
    ...
  end
  ...
end