Some SFP modules have invalid alarm/warning limits in their EPROM, for example:
Here the Rx Power alarm range is 0 dBm to 1.99 dBm, and warning range is -30 dBm to 0 dBm.
It is just a normal (but probably cheap) 1000BASE-LR transceiver.
Obviously the alarm limits are impossible since alarm/warning ranges do not overlap.
It would be useful if Observium could detect such situations and automatically ignore ranges that are impossible.