The unary + operator throws a TypeError when used with an operand of type BigInt.

console.log(+(1n)) // TypeError

The unary - operator works just fine with BigInt.

console.log(-(1n)) // -1n (although there appears to be a bug in the behavior of the Stackoverflow code editor, causing this not to render)

Why this apparent asymmetry? Is it because of the longstanding idiom of using the unary + operator to perform a conversion to Number?