Returns the minDomain from props if it exists
@param {Object} props: the props object
@param {String} axis: the current axis
@returns {Number|undefined} the minDomain based on props
function getMinFromProps(props, axis) {
  if (isPlainObject(props.minDomain) && props.minDomain[axis] !== undefined) {
    return props.minDomain[axis];
  }
  return typeof props.minDomain === "number" ? props.minDomain : undefined;
}