Update twister.cpp

More checks to be sure DM is in new format

src/twister.cpp

@@ -1092,11 +1092,15 @@ bool processReceivedDM(lazy_entry const* post)
                         libtorrent::error_code ec;
                         if (lazy_bdecode(textOut.data(), textOut.data()+textOut.size(), v, ec, &pos) == 0
                                 && v.type() == lazy_entry::dict_t) {
-                            msg = v.dict_find_string_value("msg");
-                            to = v.dict_find_string_value("to");
+                            lazy_entry const* pMsg = v.dict_find_string("msg");
+                            lazy_entry const* pTo  = v.dict_find_string("to");
+                            if (pMsg && pTo) {
+                                msg = pMsg->string_value();
+                                to  = pTo->string_value();
                                 // new features here: key distribution etc
                             }
                         }
+                    }
 
                     if( !msg.length() || !to.length() )
                         break;