custom_data is required and should be checked.

[faceless2]

After programming my EEPROM I found my hat details did not appear in /proc/device-tree-hat, until I stumbled across this:

https://forums.raspberrypi.com/viewtopic.php?p=1865033&hilit=%2Fproc%2Fdevice+tree%2Fhat#p1865033

I had

custom_data
end

adding some random data between those two lines fixed it.

As I'm at least the second person to hit this issue, could I request that eepmake is modified to fail if custom_data is empty?