Behavior when object is an error instances

[mhofman]

What should the behavior of Error.captureStackTrace be when the object provided is an object with an [[ErrorData]] slot?

My preference right now would be to reset the internal error stack info, but not add a new private field or own stack property (this is partially assuming that we standardize a prototype stack property for Errors in https://github.com/tc39/proposal-error-stacks)

[mgaudet]

I think my current implementation simply does [[Define]] a new property -- my current implementation doesn't do anything special with the [[ErrorData]] slot.

• As a result you'll get a string valued own property "stack" on the provided object with the truncated stack string.
• Using the prototype getter you could still get the un-truncated stack (and if we have code in let's say devtools that explicitly manipulates [[ErrorData]] (no idea if we do) they would ignore the own property. d

For the SES purposes, since both Error.prototype.stack and Error.captureStack trace are deniable, I think this is fine behaviour.

[mhofman]

Yeah it might be fine for a data property. Just slightly worried about the consistency of stacks depending on how you consume them.