Improve error handling

test/specs/core/createError.spec.js

@@ -0,0 +1,11 @@
+var createError = require('../../../lib/core/createError');
+
+describe('core::createError', function() {
+  it('should create an Error with message, config, and code', function() {
+    var error = createError('Boom!', { foo: 'bar' }, 'ESOMETHING');
+    expect(error instanceof Error).toBe(true);
+    expect(error.message).toBe('Boom!');
+    expect(error.config).toEqual({ foo: 'bar' });
+    expect(error.code).toBe('ESOMETHING');
+  });
+});