Additional fixes

Author: devmotion

ext/AbstractDifferentiationChainRulesCoreExt.jl

@@ -4,7 +4,7 @@ import AbstractDifferentiation as AD
 using ChainRulesCore: ChainRulesCore
 
 AD.@primitive function pullback_function(ba::AD.ReverseRuleConfigBackend, f, xs...)
-    _, back = ChainRulesCore.rrule_via_ad(ab.ruleconfig, f, xs...)
+    _, back = ChainRulesCore.rrule_via_ad(ba.ruleconfig, f, xs...)
     pullback(vs) = Base.tail(back(vs))
     pullback(vs::Tuple{Any}) = Base.tail(back(first(vs)))
     return pullback

ext/AbstractDifferentiationTrackerExt.jl

@@ -7,7 +7,7 @@ else
     using ..Tracker: Tracker
 end
 
-function AD.second_lowest(::TrackerBackend)
+function AD.second_lowest(::AD.TrackerBackend)
     return throw(ArgumentError("Tracker backend does not support nested differentiation."))
 end