Schemas can be arrays? I undersand not, if so the following looks like extra code used when schema could be an array (near line 60).:

if (schema instanceof Array) { if (!(value instanceof Array)) { return [{property:path,message:"An array tuple is required"}]; } for (i =0; i < schema.length; i++) { errors2.concat(checkProp(value[i],schema[i],path,i)); } return errors2; }