Bug: empty variables are print in email messages

[Urpokarhu1]

Hello,

There is a bug in Face-2-Face 3.9.1 (2020080400) for example message

This is to advise that your booking on the following course has been cancelled: ***BOOKING CANCELLED*** Participant: [firstname] [lastname] Course: [facetofacename] Duration: [duration] Date(s): [alldates] Location: [session:location] Venue: [session:venue] Room: [session:room]

If you leave Location, Venue and Room fields empty then in the email message sent they are displayed as:

• Location: [session:location]
• Venue: [session:venue]
• Room: [session:room]

When it should say

• Location:
• Venue:
• Room:

No need to print variable names.