  --> [ local path prefix ]/tlm_packets/channel_used_and_omitted.fpp:5:21
   |
 5 |   telemetry packets P {
   |                     ^ invalid telemetry packet set P
   |
   = note: 1 telemetry channel is both used and marked as omitted
   |
  ::: [ local path prefix ]/tlm_packets/channel_used_and_omitted.fpp:8:7
   |
 8 |       c1.T
   |       ---- c1.T is used here
   |
  ::: [ local path prefix ]/tlm_packets/channel_used_and_omitted.fpp:12:5
   |
12 |     c1.T
   |     ---- c1.T is marked omitted here

