when a stream had no channel, but it had a name, we couldn't add a ne…

[sahin52]

…w channel - bug fix

for example: my config.json is like this

.
.
.
"streams": {
    "20274": {
      "name": "20274"
    },
    "20275": {
      "name": "20275"
    },
    "49": {
      "name": "49"
    }
  }

When I try to add a channel to 49, I wasn't able to, because I was getting: time="2023-12-25T17:56:47+03:00" level=error msg="stream not found" call=StreamChannelExist channel=main func=HTTPAPIServerStreamHLSM3U8 module=http_hls stream=20275
And you could easily reproduce, remove channels from a stream and this error will occur.