fixing a couple crashes

app/build.gradle

@@ -32,7 +32,7 @@ android {
 }
 
 dependencies {
-    compile 'com.simplemobiletools:commons:2.1.2'
+    compile 'com.simplemobiletools:commons:2.1.5'
     compile 'com.davemorrissey.labs:subsampling-scale-image-view:3.6.0'
     compile 'com.theartofdev.edmodo:android-image-cropper:2.3.1'
     compile 'com.bignerdranch.android:recyclerview-multiselect:0.2'

app/src/main/kotlin/com/simplemobiletools/gallery/activities/MainActivity.kt

@@ -195,7 +195,7 @@ class MainActivity : SimpleActivity(), DirectoryAdapter.DirOperationsListener {
         for (delPath in mToBeDeleted) {
             val dir = File(delPath)
             if (dir.exists()) {
-                val files = dir.listFiles()
+                val files = dir.listFiles() ?: continue
                 files.forEach {
                     if (it.isFile && it.isImageVideoGif()) {
                         updatedFiles.add(it)

app/src/main/kotlin/com/simplemobiletools/gallery/activities/ViewPagerActivity.kt

@@ -244,7 +244,7 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
     private fun deleteDirectoryIfEmpty() {
         val file = File(mDirectory)
-        if (file.isDirectory && file.listFiles().isEmpty()) {
+        if (file.isDirectory && file.listFiles()?.isEmpty() == true) {
             file.delete()
         }
 

app/src/main/kotlin/com/simplemobiletools/gallery/asynctasks/GetDirectoriesAsynctask.kt

@@ -74,7 +74,7 @@ class GetDirectoriesAsynctask(val context: Context, val isPickVideo: Boolean, va
         media.sort()
 
         for ((name, path, isVideo, dateModified, dateTaken, size) in media) {
-            val parentDir = File(path).parent
+            val parentDir = File(path).parent ?: continue
             if (directories.containsKey(parentDir)) {
                 val directory: Directory = directories[parentDir]!!
                 val newImageCnt = directory.mediaCnt + 1