Specifies the error condition.
'preloadInconsistentData' indicates PCRF has sent an incomplete
Policy object.
'preloadAVPMissing' indicates a mandatory AVP in the preloading
message is missing.
'preloadEnforceFailure' indicates PCEF is not able to
install/modify/remove a policy preloading object.
'preloadWrongOrderFailure' indicates PCRF sent the preloading
objects in wrong order.
'preloadStaticConfigConflict' indicates PCRF tried to preload
an object, which is already statically configured in PCEF.
'preloadNoError' indicates no error has occurred so far.