Add error hint for three-argument evaluate!!

Author: penelopeysm

src/DynamicPPL.jl

@@ -226,6 +226,21 @@ if isdefined(Base.Experimental, :register_error_hint)
                 )
             end
         end
+
+        Base.Experimental.register_error_hint(MethodError) do io, exc, argtypes, _
+            is_evaluate_three_arg =
+                exc.f === AbstractPPL.evaluate!! &&
+                length(argtypes) == 3 &&
+                argtypes[1] <: Model &&
+                argtypes[2] <: AbstractVarInfo &&
+                argtypes[3] <: AbstractContext
+            if is_evaluate_three_arg
+                print(
+                    io,
+                    "\n\nThe method `evaluate!!(model, varinfo, new_ctx)` has been removed. Instead, you should store the `new_ctx` in the `model.context` field using `new_model = contextualize(model, new_ctx)`, and then call `evaluate!!(new_model, varinfo)` on the new model. (Note that, if the model already contained a non-default context, you will need to wrap the existing context.)",
+                )
+            end
+        end
     end
 end