Fix early quit exception

src/collective/behavior/featuredimage/subscriber.py

@@ -3,6 +3,9 @@
 from PIL import Image
 from plone.namedfile.file import NamedBlobImage
 from selenium import webdriver
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.support.ui import WebDriverWait
 
 import signal
 import transaction
@@ -16,13 +19,14 @@ def _get_screenshot(page):
     browser.get(page)
     data = browser.get_screenshot_as_png()
     # crop image
-    el = browser.find_element_by_id('featuredimage')
-    # XXX: quit() does not terminate PhantomJS process
-    #      https://github.com/SeleniumHQ/selenium/issues/767
-    browser.service.process.send_signal(signal.SIGTERM)
-    browser.quit()
+    el = WebDriverWait(browser, 10).until(
+        EC.presence_of_element_located((By.ID, 'featuredimage'))
+    )
+    # Put these lines after browser.quit will raise URLError exception
     location = el.location
     size = el.size
+    browser.service.process.send_signal(signal.SIGTERM)
+    browser.quit()
     im = Image.open(StringIO(data))
     im = im.crop((
         location['x'], location['y'],