message: simplify json value retrieval
diff: @@ -85,17 +85,9 @@ namespace common {
  return;
  }
  if (val.isObject()) {
  -
  - m_trackerPath = (val[DATA_KEY].isNull() && val[DATA_KEY].isString())
  - ? std::string()
  - : val[DATA_KEY].asString();
  - m_boneName =
  - (val[BONE_NAME_KEY].isNull() && val[BONE_NAME_KEY].isString())
  - ? std::string()
  - : val[BONE_NAME_KEY].asString();
  - m_articulationType = (val[ARTIC_TYPE_KEY].isNull() && val[ARTIC_TYPE_KEY].isString())
  - ? std::string()
  - : val[ARTIC_TYPE_KEY].asString();
  + m_trackerPath = val.get(DATA_KEY, "").asString();
  + m_boneName = val.get(BONE_NAME_KEY, "").asString();
  + m_articulationType = val.get(ARTIC_TYPE_KEY, "").asString();
  return;
  }
  }
  