Remove deprecated function and prevent errors in case of a null fragment name

androidApp/src/main/java/bou/amine/apps/readerforselfossv2/android/settings/SettingsActivity.kt

@@ -71,23 +71,25 @@ class SettingsActivity : AppCompatActivity(),
     }
 
     override fun onPreferenceStartFragment(
-            caller: PreferenceFragmentCompat,
-            pref: Preference
+        caller: PreferenceFragmentCompat,
+        pref: Preference
     ): Boolean {
+        val fragmentClassName = pref.fragment ?: return false
+
         // Instantiate the new Fragment
         val args = pref.extras
         val fragment = supportFragmentManager.fragmentFactory.instantiate(
-                classLoader,
-                pref.fragment
+            classLoader,
+            fragmentClassName
         ).apply {
             arguments = args
-            setTargetFragment(caller, 0)
         }
+
         // Replace the existing Fragment with the new Fragment
         supportFragmentManager.beginTransaction()
-                .replace(R.id.settings, fragment)
-                .addToBackStack(null)
-                .commit()
+            .replace(R.id.settings, fragment)
+            .addToBackStack(null)
+            .commit()
         title = pref.title
         supportActionBar?.title = title
         return true