It's the original, which is being compiled on our internal protobuf definitions in a different repository and then installed post compile as an npm module.

I spent a while trying to grok the TS error but started to suspect that it didn't make a lot of sense, so I rm -rf node_modules, reinstalled, and it went away.

It would be hard to figure out what was at fault, but it's probably a combination of the node module system, protobuf, ProtobufJS and TypeScript. I do sometimes get funny type errors and restarting TypeScript makes them go away, in this case I had to go a step further.

I'll let you know if I get this again, or figure out what happened.