navigator.share should be an optional attribute

[ghost]

navigator.share should be an optional attribute of Navigator because a significant number of browsers still don't support it (CanIUse), but it seems to be defined as always defined on the navigator interface. So, the following code:

//...
          <Tooltip
            title={
              navigator.share ? "Share" : "Your device doesn't support sharing"
            }
          >
//...

which is perfectly fine raises the following error:

This condition will always return true since the function is always defined. Did you mean to call it instead?  TS2774