Have assertString.js provide the invalid type passed to validator.

lib/util/assertString.js

@@ -3,12 +3,28 @@
 Object.defineProperty(exports, "__esModule", {
  value: true
 });
+
+var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
+
 exports.default = assertString;
 function assertString(input) {
  var isString = typeof input === 'string' || input instanceof String;
 
  if (!isString) {
- throw new TypeError('This library (validator.js) validates strings only');
+ var invalidType = void 0;
+ if (input === null) {
+ invalidType = 'null';
+ } else {
+ invalidType = typeof input === 'undefined' ? 'undefined' : _typeof(input);
+ if (invalidType === 'object' && input.constructor && input.constructor.hasOwnProperty('name')) {
+ invalidType = input.constructor.name;
+ } else {
+ invalidType = 'a ' + invalidType;
+ }
+ }
+ var message = 'This library (validator.js) validates strings only, ';
+ message += 'instead it received ' + invalidType + '.';
+ throw new TypeError(message);
  }
 }
 module.exports = exports['default'];

src/lib/util/assertString.js

@@ -2,6 +2,19 @@ export default function assertString(input) {
  const isString = (typeof input === 'string' || input instanceof String);
 
  if (!isString) {
- throw new TypeError('This library (validator.js) validates strings only');
+ let invalidType;
+ if (input === null) {
+ invalidType = 'null';
+ } else {
+ invalidType = typeof input;
+ if (invalidType === 'object' && input.constructor && input.constructor.hasOwnProperty('name')) {
+ invalidType = input.constructor.name;
+ } else {
+ invalidType = `a ${invalidType}`;
+ }
+ }
+ let message = 'This library (validator.js) validates strings only, ';
+ message += `instead it received ${invalidType}.`;
+ throw new TypeError(message);
  }
 }

validator.js

@@ -26,11 +26,30 @@
  (global.validator = factory());
 }(this, (function () { 'use strict';
 
+var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
+ return typeof obj;
+} : function (obj) {
+ return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
+};
+
 function assertString(input) {
  var isString = typeof input === 'string' || input instanceof String;
 
  if (!isString) {
- throw new TypeError('This library (validator.js) validates strings only');
+ var invalidType = void 0;
+ if (input === null) {
+ invalidType = 'null';
+ } else {
+ invalidType = typeof input === 'undefined' ? 'undefined' : _typeof(input);
+ if (invalidType === 'object' && input.constructor && input.constructor.hasOwnProperty('name')) {
+ invalidType = input.constructor.name;
+ } else {
+ invalidType = 'a ' + invalidType;
+ }
+ }
+ var message = 'This library (validator.js) validates strings only, ';
+ message += 'instead it received ' + invalidType + '.';
+ throw new TypeError(message);
  }
 }
 
@@ -63,12 +82,6 @@ function equals(str, comparison) {
  return str === comparison;
 }
 
-var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
- return typeof obj;
-} : function (obj) {
- return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
-};
-
 function toString(input) {
  if ((typeof input === 'undefined' ? 'undefined' : _typeof(input)) === 'object' && input !== null) {
  if (typeof input.toString === 'function') {