Fix type of unselectable

[Ailrun]

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[johnnyreilly]

Thanks!

[Ailrun]

Oh, it's super fast. Thanks!

[jspurlin]

@Ailrun and @johnnyreilly fyi, this is a breaking change

[rhyek]

I'm getting the following error when updating react, react-dom and their respective `@types packages:

...
    Types of property 'unselectable' are incompatible.
      Type '"off" | "on" | undefined' is not assignable to type 'boolean | undefined'.
        Type '"off"' is not assignable to type 'boolean | undefined'.

How can I fix this?

[Ailrun]

@rhyek some of your package depends on old react typing. You should check where such different typing comes.