PropType error: children must be single ReactElement

[taikn]

With the latest update (2.1.1) I get warnings like these:

Warning: Failed prop type: Invalid prop `children` of type `function` supplied to `_class`, expected a single ReactElement.

Which are caused by this line here:

react-measure/src/with-content-rect.js

Line 18 in d18b065

children: PropTypes.element,

Maybe it can be altered to something more loose to accommodate both Functions and ReactElements?

children: PropTypes.oneOfType([PropTypes.element, PropTypes.func])