Move adding the Safe extension to after the configuration is complete so that user configuration of the extensions array can't remove it.

Author: dpvc

unpacked/config/Safe.js

@@ -29,7 +29,9 @@
  *  limitations under the License.
  */
 
-if (!MathJax.Hub.config.extensions) {MathJax.Hub.config.extensions = []}
-MathJax.Hub.config.extensions.push("Safe.js");
+MathJax.Hub.Register.StartupHook("End Config", function () {
+  if (!MathJax.Hub.config.extensions) {MathJax.Hub.config.extensions = []}
+  MathJax.Hub.config.extensions.push("Safe.js");
+});
 
-MathJax.Ajax.loadComplete("[MathJax]/config/Safe.js");
+MathJax.Ajax.loadComplete("[MathJax]/config/Safe.js");