fix: Prevent uninitialized SDK warning in daemon mode. (#162)

When using daemon mode a warning would be produced on variation calls
that the SDK had not finished initialization. This situation doesn't
apply to daemon mode where we only read from the persistent store. It is
instead intended to apply to persistent store modes where the SDK is
writing to the persistence and applies to evaluations between SDK
startup and initialization being complete.

This change updates the null update process to immediately report that
it is initialized.

Author: kinyoklion

src/ldclient_update_null_server.erl

@@ -36,9 +36,11 @@ start_link(Tag) ->
 -spec init(Args :: term()) ->
     {ok, State :: state()} | {ok, State :: state(), timeout() | hibernate} |
     {stop, Reason :: term()} | ignore.
-init([_Tag]) ->
+init([Tag]) ->
     % Need to trap exit so supervisor:terminate_child calls terminate callback
     process_flag(trap_exit, true),
+    % When using the null update processor we are always initialized.
+    ldclient_update_processor_state:set_initialized_state(Tag, true),
     State = #{},
     {ok, State}.