Merge branch 'lzwandnju-master'

Author: barteksc

android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java

@@ -1019,6 +1019,10 @@ ScrollDir getScrollDir() {
     }
 
     void loadPageByOffset() {
+        if (0 == getPageCount()) {
+            return;
+        }
+
         float offset, optimal, screenCenter;
         float spacingPerPage = spacingPx - (spacingPx / getPageCount());
         if (swipeVertical) {