log errors importing or instanciating handlers

scrapy/core/downloader/handlers/__init__.py

@@ -1,5 +1,6 @@
 """Download handlers for different schemes"""
 
+import logging
 from twisted.internet import defer
 import six
 from scrapy.exceptions import NotSupported, NotConfigured
@@ -8,6 +9,9 @@ from scrapy.utils.misc import load_object
 from scrapy import signals
 
 
+logger = logging.getLogger(__name__)
+
+
 class DownloadHandlers(object):
 
     def __init__(self, crawler):
@@ -39,12 +43,16 @@ class DownloadHandlers(object):
                     'no handler available for that scheme'
             return None
 
-        dhcls = load_object(self._schemes[scheme])
         try:
+            dhcls = load_object(self._schemes[scheme])
             dh = dhcls(self._crawler_settings)
         except NotConfigured as ex:
             self._notconfigured[scheme] = str(ex)
             return None
+        except Exception as ex:
+            logger.exception()
+            self._notconfigured[scheme] = str(ex)
+            return None
         else:
             self._handlers[scheme] = dh
         return self._handlers[scheme]