Could `toString()` show causes?

[garyo]

I have to remember to import fullStack and use it when logging errors. It would be convenient if make-error-cause would override Error.prototype.toString() to print the causes as well. Perhaps that's considered too much of a change from the standard Error behavior?

[blakeembrey]

Do you want it to also include the stack trace or is this just the message strings? If so, I think it's possible. But adding the stack would mean a deviation from standard Error.prototype.toString that I don't want to introduce.

[blakeembrey]

Also for (self) reference, V1 did this but I removed it: 6de32ab. I believe there was an issue with ES2015 overwriting toString, but I really wish I had written the reasoning down in a PR now. I can try it out and come back to you.