Fix mounting APIs in route_param namespaces

lib/grape-swagger.rb

@@ -96,16 +96,25 @@ def combine_namespaces(app)
         end
       end
 
+      def determine_namespaced_routes(name, parent_route)
+        if parent_route.nil?
+          @target_class.combined_routes.values.flatten
+        else
+          parent_route.reject do |route|
+            !route_path_start_with?(route, name) || !route_instance_variable_equals?(route, name)
+          end
+        end
+      end
+
       def combine_namespace_routes(namespaces)
         # iterate over each single namespace
         namespaces.each do |name, namespace|
           # get the parent route for the namespace
           parent_route_name = extract_parent_route(name)
           parent_route = @target_class.combined_routes[parent_route_name]
+
           # fetch all routes that are within the current namespace
-          namespace_routes = parent_route.reject do |route|
-            !route_path_start_with?(route, name) || !route_instance_variable_equals?(route, name)
-          end
+          namespace_routes = determine_namespaced_routes(name, parent_route)
 
           if namespace.options.key?(:swagger) && namespace.options[:swagger][:nested] == false
             # Namespace shall appear as standalone resource, use specified name or use normalized path as name
@@ -145,7 +154,8 @@ def combine_namespace_routes(namespaces)
       def extract_parent_route(name)
         route_name = name.match(%r{^/?([^/]*).*$})[1]
         return route_name unless route_name.include? ':'
-        name.match(/\/[a-z]+/)[0].delete('/')
+        matches = name.match(/\/[a-z]+/)
+        matches.nil? ? route_name : matches[0].delete('/')
       end
 
       def sub_routes_from(parent_route, sub_namespaces)

lib/grape-swagger/doc_methods/tag_name_description.rb

@@ -4,7 +4,9 @@ class TagNameDescription
       class << self
         def build(paths)
           paths.values.each_with_object([]) do |path, memo|
-            path.values.first[:tags].each do |tag|
+            tags = path.values.first[:tags]
+            next if tags.nil?
+            tags.each do |tag|
               memo << {
                 name: tag,
                 description: "Operations about #{tag.pluralize}"