Harden thumbnail generation

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

app/src/main/java/com/owncloud/android/ui/adapter/GalleryAdapter.kt

@@ -178,10 +178,13 @@ class GalleryAdapter(
         return files.isEmpty()
     }
 
-    fun getItem(position: Int): OCFile {
+    fun getItem(position: Int): OCFile? {
         val itemCoord = getRelativePosition(position)
-
-        return files[itemCoord.section()].files[itemCoord.relativePos()]
+        return try {
+            files[itemCoord.section()].files[itemCoord.relativePos()]
+        } catch (e: ArrayIndexOutOfBoundsException) {
+            null
+        }
     }
 
     override fun isMultiSelect(): Boolean {

app/src/main/java/com/owncloud/android/ui/fragment/GalleryFragment.java

@@ -182,7 +182,6 @@ public class GalleryFragment extends OCFileListFragment {
 
     public void searchCompleted(boolean emptySearch, long lastTimeStamp) {
         photoSearchQueryRunning = false;
-        mAdapter.notifyDataSetChanged();
 
         if (mAdapter.isEmpty()) {
             setEmptyListMessage(SearchType.GALLERY_SEARCH);

app/src/main/res/layout/grid_image.xml

@@ -43,7 +43,7 @@
         android:contentDescription="@null"
         android:padding="@dimen/grid_image_icon_padding"
         android:scaleType="centerCrop"
-        android:src="@drawable/folder" />
+        android:src="@drawable/file_image" />
 
     <ImageView
         android:id="@+id/favorite_action"