XS: Set methods throw when the value argument is omitted

[d01c2]

Build environment: macOS 26.5.2

Moddable SDK version:

• Installed via jsvu, so there is no SDK source tree / git describe.
• Engine reports: XS 17.9.1, slot 32 bytes, ID 4 bytes

Target device: desktop (host xs)

Description
Set.prototype.has throws when the value argument is omitted. The same behavior occurs with Set.prototype.delete and Set.prototype.add.

An omitted argument supplies undefined, which is a valid Set value. Therefore, has and delete should return false for an empty Set, while add should add undefined and return the Set.

Steps to Reproduce

$ xst -e "Set.prototype.has.call(new Set());"
TypeError: no value (in Set.prototype.has)

Expected behavior
false is returned without an exception.

For comparison, V8 (15.3.27):

$ v8 -e "print(String(Set.prototype.has.call(new Set())))"
false

Other information
XS already produces the expected result when undefined is passed explicitly:

$ xst -e "print(String(Set.prototype.has.call(new Set(), undefined)))"
false

[phoddie]

Fixed for the September Moddable SDK.