Client crashes with: 'Exception: codec not supported: "null"'

[mz2212]

Describe the bug
When setting the codec to null for putting all sources into a meta stream, the client crashes with: Exception: codec not supported: "null"
The server however, is happy with the config.

Steps to Reproduce

1. Create sources, i.e. source = airplay:///shairport-sync?name=Airplay&codec=null
2. Add to a meta source, i.e. source = meta:///Turntable/Airplay?name=mux
3. Expect the client to choose the meta source and ignore the others, watch it crash.

Environment details

• OS: Debian sid, arm64
• Snapcast version: 0.26.0
• Installed from Debian repo

2022-11-26 17-36-36.421 [Debug] (Snapclient) Trying to get PCM device for player: alsa, parameter: , card: default
2022-11-26 17-36-36.474 [Info] (Snapclient) Version 0.26.0
2022-11-26 17-36-36.493 [Info] (Avahi) (Browser) NEW: service 'Snapcast' of type '_snapcast._tcp' in domain 'local'
2022-11-26 17-36-36.494 [Info] (Avahi) (Browser) NEW: service 'Snapcast' of type '_snapcast._tcp' in domain 'local'
2022-11-26 17-36-36.496 [Info] (Avahi) (Browser) CACHE_EXHAUSTED
2022-11-26 17-36-36.703 [Info] (Avahi) Service 'Snapcast' of type '_snapcast._tcp' in domain 'local':
2022-11-26 17-36-36.703 [Info] (Avahi)  sonogon.local:1704 (10.10.10.16)
2022-11-26 17-36-36.703 [Debug] (Avahi)         TXT=
2022-11-26 17-36-36.703 [Debug] (Avahi)         Proto=0
2022-11-26 17-36-36.703 [Debug] (Avahi)         cookie is 0
2022-11-26 17-36-36.704 [Debug] (Avahi)         is_local: 1
2022-11-26 17-36-36.704 [Debug] (Avahi)         our_own: 0
2022-11-26 17-36-36.704 [Debug] (Avahi)         wide_area: 0
2022-11-26 17-36-36.704 [Debug] (Avahi)         multicast: 1
2022-11-26 17-36-36.704 [Debug] (Avahi)         cached: 1
2022-11-26 17-36-36.708 [Info] (Controller) Found server 10.10.10.16:1704
2022-11-26 17-36-36.708 [Info] (Connection) Resolving host IP for: 10.10.10.16
2022-11-26 17-36-36.709 [Info] (Connection) Connecting
2022-11-26 17-36-36.709 [Notice] (Connection) Connected to 10.10.10.16
2022-11-26 17-36-36.710 [Info] (Connection) My MAC: "b8:27:eb:**:**:**", socket: 8
2022-11-26 17-36-36.735 [Debug] (Connection) outstanding async_write
2022-11-26 17-36-36.738 [Info] (Controller) ServerSettings - buffer: 1000, latency: 0, volume: 100, muted: 0
2022-11-26 17-36-36.738 [Debug] (Connection) Disconnecting
2022-11-26 17-36-36.740 [Debug] (Connection) Disconnected
2022-11-26 17-36-36.741 [Fatal] (Snapclient) Exception: codec not supported: "null"
2022-11-26 17-36-36.741 [Notice] (Snapclient) Snapclient terminated.

A possible fix/workaround would be to have the clients prefer to connect to the meta streams, so that the codec=null bit wouldn't even be needed.

[badaix]

Fixed: https://github.com/badaix/snapcast/releases/tag/v0.27.0