"/app/ds/run-document-server.sh: line 215: -3: substring expression < 0" error on launch

[pizzidellamaremma]

I'm on a Debian 10 and Docker environment, latest image pulled more times. After an image update (docker-compose pull | docker-compose up -d) I'm stuck with this simple log lines:

/app/ds/run-document-server.sh: line 215: -3: substring expression < 0
nc: port number invalid: 
Waiting for connection to the  host on port 

It seems it is crashing right here: (from run-document-server.sh)

  # extract the path (if any)
  local path="$(echo $url | grep / | cut -d/ -f2-)"

  AMQP_SERVER_PROTO=${proto:0:-3}    #  <---
  AMQP_SERVER_HOST=$host
  AMQP_SERVER_USER=$user
  AMQP_SERVER_PASS=$pass
  AMQP_SERVER_PORT=$port
}