BLDC motor control hall effect invalid
You could implement back-emf as a backup control system to aid detecting fault conditions matching sensor data and rotor position calculated by back-emf, thus being able to detect even those fault conditions producing a "good looking" set of values, and eventually bring the motor to a soft stop using BEMF for rotor position detection.

Another option, if you want to go the fault detection way, is to implement redundancy in your sensors and communication line.
This can be implemented in various ways and probably is the best way to add a functional fault detection that not only detect faults but also enables you to not have to immediately halt the motor. 

If both such solutions seems too complicate you probably are in a case were a serious fault detection algorithm is not needed and stopping the motor in case of incoherent data is "just the right solution" so you can fix that cold soldered hall sensor  before finals :-)

As far as fault detection goes is probably more important to focus on current detection.

Have fun! :-)