Fix modal dispose scroll reset

js/src/modal.js

@@ -144,6 +144,12 @@ class Modal extends BaseComponent {
     EventHandler.off(window, EVENT_KEY)
     EventHandler.off(this._dialog, EVENT_KEY)
 
+    if (this._isShown) {
+      document.body.classList.remove(CLASS_NAME_OPEN)
+      this._resetAdjustments()
+      this._scrollBar.reset()
+    }
+
     this._backdrop.dispose()
     this._focustrap.deactivate()
 

js/tests/unit/modal.spec.js

@@ -861,6 +861,27 @@ describe('Modal', () => {
       expect(spyOff).toHaveBeenCalledTimes(3)
       expect(spyDeactivate).toHaveBeenCalled()
     })
+
+    it('should reset scrollbars when disposing a shown modal', () => {
+      return new Promise(resolve => {
+        fixtureEl.innerHTML = '<div id="exampleModal" class="modal"><div class="modal-dialog"></div></div>'
+
+        const modalEl = fixtureEl.querySelector('.modal')
+        const modal = new Modal(modalEl)
+        const spyReset = spyOn(ScrollBarHelper.prototype, 'reset').and.callThrough()
+
+        modalEl.addEventListener('shown.bs.modal', () => {
+          modal.dispose()
+
+          expect(spyReset).toHaveBeenCalled()
+          expect(document.body).not.toHaveClass('modal-open')
+          expect(document.body.style.overflow).toEqual('')
+          resolve()
+        })
+
+        modal.show()
+      })
+    })
   })
 
   describe('handleUpdate', () => {