To reproduce, attempt to send a message such as:
echo 'hello "world"...' | slack chat send --channel test --pretext "a test message"
You will receive an error:
{
"ok": false,
"error": "no_text"
}
I believe this is due to the way the JSON body is built in https://github.com/rockymadden/slack-cli/blob/master/src/slack#L224 where quote marks aren't escaped.
Update: Due to my frustration with this, I created a new tool which is just designed to do one thing - post text messages to Slack: https://github.com/TJC/simple-slack-message