fix(navcontrollerbase): fixes crash when it is destroyed

fixes #11338

src/navigation/nav-controller-base.ts

@@ -216,6 +216,10 @@ export class NavControllerBase extends Ion implements NavController {
   }
 
   _success(result: NavResult, ti: TransitionInstruction) {
+    if (this._queue === null) {
+      this._fireError('nav controller was destroyed', ti);
+      return;
+    }
     this._init = true;
     this._trnsId = null;
 
@@ -237,6 +241,10 @@ export class NavControllerBase extends Ion implements NavController {
   }
 
   _failed(rejectReason: any, ti: TransitionInstruction) {
+    if (this._queue === null) {
+      this._fireError('nav controller was destroyed', ti);
+      return;
+    }
     this._trnsId = null;
     this._queue.length = 0;
 
@@ -245,6 +253,10 @@ export class NavControllerBase extends Ion implements NavController {
     this._swipeBackCheck();
     this._nextTrns();
 
+    this._fireError(rejectReason, ti);
+  }
+
+  _fireError(rejectReason: any, ti: TransitionInstruction) {
     if (ti.done) {
       ti.done(false, false, rejectReason);
     }

src/navigation/test/nav-controller.spec.ts

@@ -1068,6 +1068,23 @@ describe('NavController', () => {
 
   });
 
+  describe('destroy', () => {
+
+    it('should not crash when destroyed while transitioning', (done) => {
+      let view1 = mockView(MockView1);
+      nav.push(view1).then(() => {
+        fail('it should not succeed');
+        done();
+      }).catch((err: any) => {
+        expect(err).toEqual('nav controller was destroyed');
+        done();
+        });
+      nav.destroy();
+    }, 10000);
+
+  });
+
+
   let nav: NavControllerBase;
   let trnsDone: jasmine.Spy;