Fix #4482 (#4484)

Author: madhurgupta10

app/src/main/java/fr/free/nrw/commons/media/MediaDetailPagerFragment.java

@@ -12,6 +12,9 @@
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
+import androidx.appcompat.app.ActionBar;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentStatePagerAdapter;
@@ -89,9 +92,18 @@ public View onCreateView(LayoutInflater inflater,
         pager.addOnPageChangeListener(this);
 
         adapter = new MediaDetailAdapter(getChildFragmentManager());
+
         ((BaseActivity)getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
+        if (getActivity() != null) {
+            final ActionBar actionBar = ((AppCompatActivity) getActivity()).getSupportActionBar();
+            if (actionBar != null) {
+                actionBar.setDisplayHomeAsUpEnabled(true);
+            }
+        }
+
         pager.setAdapter(adapter);
+
         if (savedInstanceState != null) {
             final int pageNumber = savedInstanceState.getInt("current-page");
             pager.setCurrentItem(pageNumber, false);