fix(nav): fixes empty stack condition

Author: manucorporat

src/components/input/input-base.ts

@@ -340,7 +340,7 @@ export class InputBase extends Ion {
       // do not allow any clicks while it's scrolling
       var scrollDuration = getScrollAssistDuration(scrollData.scrollAmount);
       this._app.setEnabled(false, scrollDuration);
-      this._nav && this._nav.setTransitioning(true, scrollDuration);
+      this._nav && this._nav.setTransitioning(true);
 
       // temporarily move the focus to the focus holder so the browser
       // doesn't freak out while it's trying to get the input in place

src/navigation/nav-controller-base.ts

@@ -335,15 +335,6 @@ export class NavControllerBase extends Ion implements NavController {
 
   _postViewInit(enteringView: ViewController, leavingView: ViewController, ti: TransitionInstruction, resolve: TransitionResolveFn) {
     assert(leavingView || enteringView, 'Both leavingView and enteringView are null');
-
-    if (!enteringView && !this._isPortal) {
-      console.warn(`You can't remove all the pages in the navigation stack. nav.pop() is probably called too many times.`,
-        this, this.getNativeElement());
-
-      ti.reject && ti.reject('navigation stack needs at least one root page');
-      return false;
-    }
-
     const opts = ti.opts || {};
     const insertViews = ti.insertViews;
     const removeStart = ti.removeStart;
@@ -366,6 +357,16 @@ export class NavControllerBase extends Ion implements NavController {
       opts.direction = opts.direction || DIRECTION_BACK;
     }
 
+    const finalBalance = this._views.length + (insertViews ? insertViews.length : 0) - (destroyQueue ? destroyQueue.length : 0);
+    assert(finalBalance >= 0, 'final balance can not be negative');
+    if (finalBalance === 0 && !this._isPortal) {
+      console.warn(`You can't remove all the pages in the navigation stack. nav.pop() is probably called too many times.`,
+        this, this.getNativeElement());
+
+      ti.reject && ti.reject('navigation stack needs at least one root page');
+      return false;
+    }
+
     // there are views to insert
     if (insertViews) {
       // manually set the new view's id if an id was passed in the options