JSX.Element don't have children prop.

[Aloento]

If you use Typescript to try this #919
Then you will find your JSX.Element (VNode<any>) from wmr didn't have the children property.

It's a very annoying error.

[rschristian]

It doesn't look like this is related to WMR.

Preact and React aren't fully compatible when it comes to types, and it looks like you're using something that was meant for React.

[rschristian]

Interestingly I get a different error in my editor when looking at this:

[tsserver 2786] [E] 'HelmetProvider' cannot be used as a JSX component.
  Its instance type 'HelmetProvider' is not a valid JSX element.
    Type 'HelmetProvider' is missing the following properties from type 'Component<any, any>': state, props, context, setState, and 2 more.

Do you have any TSConfig alterations made?

[Aloento]

No, TSConfig is the original version.
I prepare this for you
https://github.com/Aloento/WMR