问为什么在部署后google应用引擎中出现500服务器错误？

EN

import webapp2
import sys
sys.path.insert(0, 'libs')
import requests
from bs4 import *
import re
import smtplib
from google.appengine.api import urlfetch
from google.appengine import runtime

class MainHandler(webapp2.RequestHandler):
  def get(self):
    self.response.write("hello")

    #urlfetch.set_default_fetch_deadline(60)

  def spider():
    count = 1
    href = 'www.example.com'
    while count <= 2:
      new_url = href
      new_source_code = urlfetch.fetch(new_url, deadline=60)
      new_plain_text = new_source_code.content
      new_soup = BeautifulSoup(new_plain_text)
      for new_link in new_soup.find_all('table'):
        for new_link1 in new_link.find_all('a'):
          new_href = 'www.example.com' + new_link1.get('href')
          new1_url = new_href
          new1_source_code = urlfetch.fetch(new1_url, deadline=60)
          new1_plain_text = new1_source_code.content
          new1_soup = BeautifulSoup(new1_plain_text)
          for new1_link in new1_soup.find_all('tbody'):
            for new1_link1 in new1_link.find_all('a', attrs={'class': 'title'}):
              new1_title = new1_link1.string
              new1_title = new1_title.strip()
              new1_href = 'www.example.com' + new1_link1.get('href')
              self.response.write(new1_title)
              self.response.write(new1_href)
    count = count + 1

  spider()

app = webapp2.WSGIApplication([
    ('/', MainHandler)
], debug=True)