Restrict spreading for Instantiable Type with non object constraint

[collin5]

i.e

function f1<T extends number>(arg: T) {
  return { ...arg }; // should error "Spread types may only be created from object types."
}

function f2<T extends number | { [key: string]: any }>(arg: T) {
  return { ...arg } // should also error
}

#30851 - Partially resolves

[collin5]

Updated!

[orta]

Yep, this looks good to me - thanks @collin5. let's get this is. I've commented in #30851 about unknown being something we're open to having a PR closing 👍

[collin5]

Thank you.