Fix crash when trying to save with no scenes and scripts open

This could occur when attempting to save project settings when
no scenes or scripts are open (which is common in a brand new project).

(cherry picked from commit 16876bec76528ce5c4e84aad66bc98cdbcd62e97)

editor/plugins/script_editor_plugin.cpp

@@ -2151,8 +2151,7 @@ bool ScriptEditor::edit(const RES &p_resource, int p_line, int p_col, bool p_gra
 
 void ScriptEditor::save_current_script() {
 	ScriptEditorBase *current = _get_current_editor();
-
-	if (_test_script_times_on_disk()) {
+	if (!current || _test_script_times_on_disk()) {
 		return;
 	}