[lammps-users] hybrid airebo + class2

The error tells you what the problem is. A mis-formatted
data file. If you look at the section where the line is,
you will see you have an extra blank line after Bond Coeffs,
as well as several other places.

This problem seems to have nothing to do with the original
issue you posted about which was using AIREBO with a bonded
system and getting bad energies. The system you describe
below, bonds between non-AIREBO atoms should be possible
to do in LAMMPS without any problem. If you put bonds
between AIREBO atoms and define special_bonds, then
you will have problems, but as stated previously that kind
of model doesn't really make sense.