I've just got around to testing this with my DHT22 (uploaded to an ESP-01 10 minutes ago) and I'm also occasionally getting negative numbers. As well as that I'm getting a lot of checksum errors that I wasn't getting with the old library.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I've just got around to testing this with my DHT22 (uploaded to an ESP-01 10 minutes ago) and I'm also occasionally getting negative numbers. As well as that I'm getting a lot of checksum errors that I wasn't getting with the old library.
Here are some results, in case they're useful: