fixed iteration over additional properties

Author: fiddlededee

lib/beautifier.js

@@ -59,7 +59,7 @@ const beautifySchema = (schema) => {
   if (!schema.example) schema.generatedExample = generateExample(schema);
 
   _.each(schema.properties, beautifySchema);
-  _.each(schema.additionalProperties, beautifySchema);
+  if (schema.additionalProperties) _.each(schema.additionalProperties.properties, beautifySchema);
   if (schema.items) beautifySchema(schema.items);
 
   return schema;