[WPE][GTK] Fix default return value for webkit_settings_get_webrtc_udp_ports_range()

https://bugs.webkit.org/show_bug.cgi?id=281742

Reviewed by Carlos Garcia Campos.

* Source/WebKit/UIProcess/API/glib/WebKitSettings.cpp:
(webkit_settings_get_webrtc_udp_ports_range):

Canonical link: https://commits.webkit.org/285399@main

Author: philn

Source/WebKit/UIProcess/API/glib/WebKitSettings.cpp

@@ -4513,7 +4513,7 @@ void webkit_settings_set_enable_ice_candidate_filtering(WebKitSettings* settings
 const gchar*
 webkit_settings_get_webrtc_udp_ports_range(WebKitSettings* settings)
 {
-    g_return_val_if_fail(WEBKIT_IS_SETTINGS(settings), FALSE);
+    g_return_val_if_fail(WEBKIT_IS_SETTINGS(settings), nullptr);
 #if ENABLE(WEB_RTC)
     return settings->priv->webrtcUDPPortsRange.data();
 #else