raise a more informative NoMethodError for missing custom queries

lib/valkyrie/persistence/custom_query_container.rb

@@ -47,7 +47,11 @@ def register_query_handler(query_handler)
     end
 
     def method_missing(meth_name, *args, &block)
-      query_handler = find_query_handler(meth_name).new(query_service: query_service)
+      handler_class =
+        find_query_handler(meth_name) ||
+        raise(NoMethodError, "Custom query #{meth_name} is not registered. The registered queries are: #{queries}")
+
+      query_handler = handler_class.new(query_service: query_service)
       return super unless query_handler
       query_handler.__send__(meth_name, *args, &block)
     end
@@ -59,5 +63,11 @@ def find_query_handler(method)
     def respond_to_missing?(meth_name, _args)
       find_query_handler(meth_name).present?
     end
+
+    private
+
+    def queries
+      query_handlers.map(&:queries).flatten
+    end
   end
 end

lib/valkyrie/specs/shared_specs/queries.rb

@@ -464,6 +464,13 @@ class Valkyrie::Specs::ChildWithOrderedParents < Valkyrie::Resource
     end
   end
 
+  describe ".custom_queries" do
+    it "raises NoMethodError when the custom query does not exist" do
+      expect(query_service.custom_queries).not_to respond_to :very_fake_query
+      expect { query_service.custom_queries.very_fake_query }.to raise_error(NoMethodError)
+    end
+  end
+
   describe ".register_query_handler" do
     it "can register a query handler" do
       class QueryHandler