Replace unsafe null assertion with safe call.

Author: tuancoltech

app/src/main/java/ai/elimu/content_provider/language/LanguageListDialogFragment.kt

@@ -90,7 +90,7 @@ class LanguageListDialogFragment : BottomSheetDialogFragment() {
                         MainActivity::class.java
                     )
                     startActivity(mainActivityIntent)
-                    activity!!.finish()
+                    activity?.finish()
                 }
             })
         }