Issue Summary

Attempting to use a Discord URL with the Slack integration will fail with an error of "Token can't be blank." This was previously supported.

Steps to Reproduce

1. Create a Discord Server
2. Go to Server Settings > Integrations > Create Webhook
3. This provides a URL in the format of https://discordapp.com/api/webhooks/WEBHOOK_ID/TOKEN_HERE/slack
4. Add the webhook URL in Apps > Slack

Expected Results

Discord URL is subscribed, update are sent to Discord

Actual Results

Fails with error "Token can't be blank"

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available