placeholder {speakers} in update mail does not work

[Kunsi]

Current Behavior

Template is saved without error, releasing a schedule fails with error 500

Expected Behavior

Template creation fails (see #215)

Steps to Reproduce

1. Add {speakers} somewhere in mail template for schedule update mail
2. Try to release a schedule

Your Environment

• Version used: v1.1.1
• Link to your instance, if in production: https://talks.seibert-media.net/
• Error Log: https://gist.github.com/Kunsi/61c49937d2cddca34135122ffa8c3f8d

[rixx]

Thank you for the detailed report!

[rixx]

Do you need a bugfix release for this?

[Kunsi]

No, thanks for asking :)