Error: type mismatch: got <nil> but expected 'string'
## Get an error when trying to compile with Jester.
```bash
/home/flairfocus/.nimble/pkgs/httpbeast-0.2.0/httpbeast.nim(58, 44) Error: type mismatch: got <nil> but expected 'string'
```

## Nim Info
```bash
$ nim -v
Nim Compiler Version 0.18.1 [Linux: amd64]
Compiled at 2018-08-18
Copyright (c) 2006-2018 by Andreas Rumpf

active boot switches: -d:release
```