Support for Error Cause

[petamoriken]

Pony Cause (Error Cause ponyfill) has stackWithCauses function that generate a stack trace string with cause errors. Make sense to add function like System.getStackStringWithCauses.

Error: something really bad happened here: something bad happened
    at Object.<anonymous> (/examples/fullStack.js:5:12)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)
    at startup (node.js:139:18)
    at node.js:968:3
caused by: Error: something bad happened
    at Object.<anonymous> (/examples/fullStack.js:3:12)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)
    at startup (node.js:139:18)
    at node.js:968:3

This feature has nothing to do with compatibility, which is the motivation for this proposal, so it may be better to proceed as a separate proposal. However, I thought it was worth having this issue here for discussion.

related: #22, tc39/proposal-error-cause#16, tc39/proposal-error-cause#41

[ljharb]

If engines decide to decorate the stack with causes, then this proposal will have to accommodate it. If not, it won't.

Either way, until this proposal (or another that does the same thing) lands, no proposal would be able to do anything with error stacks. I'm not sure what there is to discuss.

[petamoriken]

If engines decide to decorate the stack with causes, then this proposal will have to accommodate it. If not, it won't.

Since sentry-javascript and others already assume that Error.prototype.stack does not contain cause errors, it will not be possible to extend it to prevent double printing. Adding it as a separate function is preferable.

Either way, until this proposal (or another that does the same thing) lands, no proposal would be able to do anything with error stacks. I'm not sure what there is to discuss.

That's true. The discussion will start when this proposal (or another) reaches Stage 2 or 3. I prepared for that time. If this issue is in your way, you can close it.

[erights]

Thanks for filing. Please keep it open. The SES-shim currently has a partial shim for getStackString. We will need to update that somehow for causes regardless. Will be good to track that here.