#402: Don't fail if captureStackTrace is not a function (#410)

Author: aldermoovel

lib/JsonWebTokenError.js

@@ -1,6 +1,8 @@
 var JsonWebTokenError = function (message, error) {
   Error.call(this, message);
-  Error.captureStackTrace(this, this.constructor);
+  if(Error.captureStackTrace) {
+    Error.captureStackTrace(this, this.constructor);
+  }
   this.name = 'JsonWebTokenError';
   this.message = message;
   if (error) this.inner = error;
@@ -9,4 +11,4 @@ var JsonWebTokenError = function (message, error) {
 JsonWebTokenError.prototype = Object.create(Error.prototype);
 JsonWebTokenError.prototype.constructor = JsonWebTokenError;
 
-module.exports = JsonWebTokenError;
+module.exports = JsonWebTokenError;