message: FunctionDef: add the ability to retrieve params via std::optional<>.
diff: @@ -80,12 +80,17 @@ struct HandlerContext {
  size_t parameterCount() const noexcept { return parameters.size(); }
  - FunctionParam param_or(size_t _index, FunctionParam _defaultValue) const noexcept
  + std::optional<FunctionParam> param_opt(size_t _index) const noexcept
  {
  if (_index < parameters.size() && parameters[_index])
  - return parameters[_index];
  + return {parameters[_index]};
  else
  - return _defaultValue;
  + return std::nullopt;
  + }
  +
  + FunctionParam param_or(size_t _index, FunctionParam _defaultValue) const noexcept
  + {
  + return param_opt(_index).value_or(_defaultValue);
  }
  unsigned int param(size_t _index) const noexcept
  