Fix LogDensityAt struct

Author: penelopeysm

src/logdensityfunction.jl

@@ -212,7 +212,18 @@ struct LogDensityAt{M<:Model,V<:AbstractVarInfo,C<:AbstractContext}
 end
 function (ld::LogDensityAt)(x::AbstractVector)
     varinfo_new = unflatten(ld.varinfo, x)
-    return getlogp(last(evaluate!!(ld.model, varinfo_new, ld.context)))
+    varinfo_eval = last(evaluate!!(ld.model, varinfo_new, ld.context))
+    has_prior = hasacc(varinfo_eval, Val(:LogPrior))
+    has_likelihood = hasacc(varinfo_eval, Val(:LogLikelihood))
+    if has_prior && has_likelihood
+        return getlogjoint(varinfo_eval)
+    elseif has_prior
+        return getlogprior(varinfo_eval)
+    elseif has_likelihood
+        return getloglikelihood(varinfo_eval)
+    else
+        error("LogDensityFunction: varinfo tracks neither log prior nor log likelihood")
+    end
 end
 
 ### LogDensityProblems interface