Small improvement

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -196,6 +196,7 @@ import java.util.Objects;
 import java.util.Properties;
 
 import javax.mail.Address;
+import javax.mail.MessageRemovedException;
 import javax.mail.MessagingException;
 import javax.mail.Session;
 import javax.mail.internet.InternetAddress;
@@ -5251,7 +5252,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                 DB db = DB.getInstance(context);
                 EntityMessage message = db.message().getMessage(id);
                 if (message == null)
-                    throw new FileNotFoundException("message gone");
+                    throw new MessageRemovedException();
                 File file = message.getRawFile(context);
                 Log.i("Raw file=" + file);
 
@@ -5302,7 +5303,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
             protected void onException(Bundle args, Throwable ex) {
                 if (ex instanceof IllegalArgumentException || ex instanceof FileNotFoundException)
                     Snackbar.make(view, ex.getMessage(), Snackbar.LENGTH_LONG).show();
-                else
+                else if (!(ex instanceof MessageRemovedException))
                     Log.unexpectedError(getParentFragmentManager(), ex);
             }
         }.execute(this, args, "raw:save");