[BUGFIX] Access trigger element in modal correctly

$(this) does not work in TypeScript, as this is bound to the class or the
method, but never to the element. Thus, the target element is fetched
from the event.

Resolves: #84138
Releases: master
Change-Id: I05545d19f5cb10adc3678fa81d81e3b181047bc4
Reviewed-on: https://review.typo3.org/56007
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Tobi Kretschmann <tobi@tobishome.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/backend/Resources/Private/TypeScript/Modal.ts

@@ -430,14 +430,14 @@ class Modal {
     });
 
     // Remove modal from Modal.instances when hidden
-    currentModal.on('hidden.bs.modal', (): void => {
+    currentModal.on('hidden.bs.modal', (e: JQueryEventObject): void => {
       if (this.instances.length > 0) {
         const lastIndex = this.instances.length - 1;
         this.instances.splice(lastIndex, 1);
         this.currentModal = this.instances[lastIndex - 1];
       }
       currentModal.trigger('modal-destroyed');
-      $(this).remove();
+      $(e.currentTarget).remove();
       // Keep class modal-open on body tag as long as open modals exist
       if (this.instances.length > 0) {
         $('body').addClass('modal-open');