Airframe comments parsing corner case

[MaEtUgR]

Describe the bug
If you do not specify an @maintainer tag in your airframe configuration but put a comment afterwards then the parsing fails with an unexpected error.

@cmic0 found the bug originally.

To Reproduce
Steps to reproduce the behavior:

1. Replace the maintainer line of an airframe configuration e.g. https://github.com/PX4/Firmware/blob/master/ROMFS/px4fmu_common/init.d/airframes/4001_quad_x#L20 with # Some comment
2. Do make clean
3. Build e.g. make px4_fmu-v5
4. See error

Expected behavior
The parser should either still work without maintainer tag or ask for a maintainer but not fail unexpectedly in the parsing state machine.

Log Files and Screenshots

[0/1294] git submodule platforms/nuttx/NuttX/nuttx
[1/1294] Creating airframes.xml
FAILED: airframes.xml 
cd /home/maetugr/Firmware/build/px4_fmu-v5_default && /usr/bin/python3 /home/maetugr/Firmware/Tools/px_process_airframes.py --airframes-path /home/maetugr/Firmware/ROMFS/px4fmu_common/init.d --board CONFIG_ARCH_BOARD_px4_fmu-v5 --xml /home/maetugr/Firmware/build/px4_fmu-v5_default/airframes.xml
Traceback (most recent call last):
  File "/home/maetugr/Firmware/Tools/px_process_airframes.py", line 138, in <module>
    main()
  File "/home/maetugr/Firmware/Tools/px_process_airframes.py", line 102, in main
    if not scanner.ScanDir(args.airframes_path, parser):
  File "/home/maetugr/Firmware/Tools/px4airframes/srcscanner.py", line 22, in ScanDir
    if not self.ScanFile(path, parser):
  File "/home/maetugr/Firmware/Tools/px4airframes/srcscanner.py", line 38, in ScanFile
    return parser.Parse(path, contents)
  File "/home/maetugr/Firmware/Tools/px4airframes/srcparser.py", line 366, in Parse
    tags[current_tag] += "\n" + comment_content
KeyError: 'output'
[7/1294] ROMFS: copying, generating airframes
FAILED: genromfs/init.d/rcS genromfs/init.d/rc.serial genromfs/init.d/rc.autostart genromfs/init.d/rc.autostart.post ROMFS/romfs_copy.stamp 
cd /home/maetugr/Firmware/build/px4_fmu-v5_default/ROMFS && /usr/bin/cmake -E remove_directory /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs && /usr/bin/cmake -E copy_directory /home/maetugr/Firmware/ROMFS/px4fmu_common /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs && /usr/bin/cmake -E remove_directory /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d-posix && /usr/bin/cmake -E remove_directory /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/mixers-sitl && /usr/bin/cmake -E remove /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/mixers/CMakeLists.txt && /usr/bin/cmake -E remove /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d/CMakeLists.txt && /usr/bin/cmake -E remove /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d/airframes/CMakeLists.txt && /usr/bin/python3 /home/maetugr/Firmware/Tools/px_process_airframes.py --airframes-path /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d --start-script /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d/rc.autostart --board px4_fmu-v5 && /usr/bin/python3 /home/maetugr/Firmware/Tools/serial/generate_config.py --rc-dir /home/maetugr/Firmware/build/px4_fmu-v5_default/genromfs/init.d --serial-ports GPS1:/dev/ttyS0 TEL1:/dev/ttyS1 TEL2:/dev/ttyS2 TEL4:/dev/ttyS3 --config-files /home/maetugr/Firmware/src/lib/battery/module.yaml /home/maetugr/Firmware/src/drivers/distance_sensor/cm8jl65/module.yaml /home/maetugr/Firmware/src/drivers/distance_sensor/leddar_one/module.yaml /home/maetugr/Firmware/src/drivers/distance_sensor/sf0x/module.yaml /home/maetugr/Firmware/src/drivers/distance_sensor/tfmini/module.yaml /home/maetugr/Firmware/src/drivers/distance_sensor/ulanding_radar/module.yaml /home/maetugr/Firmware/src/drivers/dshot/module.yaml /home/maetugr/Firmware/src/drivers/gps/module.yaml /home/maetugr/Firmware/src/drivers/rc_input/module.yaml /home/maetugr/Firmware/src/drivers/roboclaw/module.yaml /home/maetugr/Firmware/src/drivers/telemetry/frsky_telemetry/module.yaml /home/maetugr/Firmware/src/drivers/telemetry/hott/hott_telemetry/module.yaml /home/maetugr/Firmware/src/drivers/telemetry/iridiumsbd/module.yaml /home/maetugr/Firmware/src/modules/battery_status/module.yaml /home/maetugr/Firmware/src/modules/mavlink/module.yaml && /usr/bin/cmake -E touch romfs_copy.stamp
Traceback (most recent call last):
  File "/home/maetugr/Firmware/Tools/px_process_airframes.py", line 138, in <module>
    main()
  File "/home/maetugr/Firmware/Tools/px_process_airframes.py", line 102, in main
    if not scanner.ScanDir(args.airframes_path, parser):
  File "/home/maetugr/Firmware/Tools/px4airframes/srcscanner.py", line 22, in ScanDir
    if not self.ScanFile(path, parser):
  File "/home/maetugr/Firmware/Tools/px4airframes/srcscanner.py", line 38, in ScanFile
    return parser.Parse(path, contents)
  File "/home/maetugr/Firmware/Tools/px4airframes/srcparser.py", line 366, in Parse
    tags[current_tag] += "\n" + comment_content
KeyError: 'output'
[11/1294] Generating uORB topic headers
ninja: build stopped: subcommand failed.
make: *** [Makefile:202: px4_fmu-v5] Error 1

I had a quick look but didn't see the problem immediately... probably needs debugging if important enough.

[JacobCrabill]

I think I encountered this error a while back too - I don't think general non-tag comments are supported by the parser. My solution was to add a "@desc" tag that is ignored by the parser, allowing you to write a multi-line comment. I can put a PR in for this (pretty small change).