fix #555, check if file exists at viewpager activity

app/build.gradle

@@ -42,7 +42,7 @@ ext {
 }
 
 dependencies {
-    implementation 'com.simplemobiletools:commons:3.5.11'
+    implementation 'com.simplemobiletools:commons:3.6.0'
     implementation 'com.davemorrissey.labs:subsampling-scale-image-view:3.9.0'
     implementation 'com.theartofdev.edmodo:android-image-cropper:2.6.0'
     implementation 'com.android.support:multidex:1.0.2'

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

@@ -177,6 +177,13 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
             return
         }
 
+        val file = File(mPath)
+        if (!file.exists()) {
+            deleteFromMediaStore(file)
+            finish()
+            return
+        }
+
         if (intent.extras?.containsKey(IS_VIEW_INTENT) == true) {
             if (isShowHiddenFlagNeeded()) {
                 if (!config.isPasswordProtectionOn) {
@@ -189,7 +196,7 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
         showSystemUI()
 
-        mDirectory = File(mPath).parent
+        mDirectory = file.parent
         supportActionBar?.title = mPath.getFilenameFromPath()
 
         view_pager.onGlobalLayout {