Audited all calls for Printf. Noticed the following in some logs
```
jsonrpc2 handler: sending response {1 %!d(string=) %!d(bool=false)}: jsonrpc2: connection is closed
```
I accidentally made this change in the main repo, instead of here.
This ensures that the server can tell the difference between a response and a request. The old method (resp == nil) didn't work because we use interfaces here, and the interfaces would often have types, but not values.
