Use slightly better error message when unable to find Sequel::Model i…

…nstance

lib/fixture_dependencies/sequel.rb

@@ -10,7 +10,7 @@ def add_associated_object_S(reflection, attr, object, assoc)
   end
 
   def model_find_S(model, pk)
-    model[pk] || raise(Sequel::Error)
+    model[pk] || raise_model_error_S("No matching record for #{model.name}[#{pk.inspect}]")
   end
 
   def model_find_by_pk_S(model, pk)