luci-base: prevent save/traceback race for _state

A _state race is possible during save when a refresh is in
progress. Attempt to avoid it by not nulling state prior
to refresh.

Signed-off-by: Paul Donald <newtwen+github@gmail.com>

modules/luci-base/htdocs/luci-static/resources/network.js

@@ -354,7 +354,6 @@ function initNetworkState(refresh) {
 	if (_state == null || refresh) {
 		const hasWifi = L.hasSystemFeature('wifi');
 
-		if (refresh) _state = null;
 		if (refresh || !_init) {
 			_init = Promise.all([
 			L.resolveDefault(callNetworkInterfaceDump(), []),
@@ -538,6 +537,9 @@ function initNetworkState(refresh) {
 
 	}
 
+	if (refresh)
+		return _init;
+
 	return (_state != null ? Promise.resolve(_state) : _init);
 }