`error` and `completed` events not emitted on v6

[0xOlias]

The docs mention error and completed events, but these are not being emitted on v6. I suspect that this is the root cause of a number of open issues (#171, #169).

I would take a stab at a PR to add them, but I'm not sure how the release process works for v6.

[sindresorhus]

v6 is no longer supported. Are these issues reproducible on v7?

[0xOlias]

I'm not sure. I didn't realize v6 was unsupported, that's unfortunate. Feel free to close.

[darky]

Would be better to support v6 too, seems very hard to shift community from cjs -> esm