Array.prototype.toSpliced does this:

12. If newLen > 2^53 - 1, throw a TypeError exception.
13. Let A be ? ArrayCreate(𝔽(newLen)).

But ArrayCreate does this:

1. If length > 2^32 - 1, throw a RangeError exception.

Couple of issues:

• Why is the length validated to be in a range much larger than the immediate next step allows in the first place?
• Why TypeError and not RangeError - this seems to be inherited from Array.prototype.splice, which uses ArraySpeciesCreate and only passes actualDeleteCount as the length in the next step however
• Is it intentional that depending on how much too large (i.e. above 2^32 - 1) the value is you'll get a different error type?