`sign` crashes with `validator.isValid is not a function` for certain objects

[ej-shafran]

`sign` crashes with `validator.isValid is not a function` for certain objects

[ej-shafran]

I looked into the source code some more. Seems the issue is that the code iterates over the keys of the object (in validate) and checks for a validator by accessing schema[key]. In the case of keys like toString, __proto__, and valueOf, it does find a value, so the if (!validator) check doesn't trigger. It then tries to call validator.isValid, but since it's a function (or the prototype of the object), it crashes....

[ej-shafran]

Managed to fix this by doing:

 function validate(schema, allowUnknown, object, parameterName) {
   if (!isPlainObject(object)) {
     throw new Error('Expected "' + parameterName + '" to be a plain object.');
   }
   Object.keys(object)
     .forEach(function(key) {
-      const validator = schema[key];
-      if (!validator) {
+     if (!Object.getOwnPropertyNames(schema).includes(key)) {
         if (!allowUnknown) {
           throw new Error('"' + key + '" is not allowed in "' + parameterName + '"');
         }
         return;
       }
+      const validator = schema[key];
       if (!validator.isValid(object[key])) {
         throw new Error(validator.message);
       }
     });
 }

(Though it's probably better to use Object.hasOwnProperty or lodash.has instead)