Added timeout in error handling [(#1636)](GoogleCloudPlatform/python-docs-samples#1636)

Author: anguillanneuf

samples/snippets/publisher.py

@@ -131,7 +131,8 @@ def publish_messages_with_error_handler(project, topic_name):
     topic_path = publisher.topic_path(project, topic_name)
 
     def callback(message_future):
-        if message_future.exception():
+        # When timeout is unspecified, the exception method waits indefinitely.
+        if message_future.exception(timeout=30):
             print('Publishing message on {} threw an Exception {}.'.format(
                 topic_name, message_future.exception()))
         else:

samples/snippets/subscriber.py

@@ -223,12 +223,12 @@ def callback(message):
     # Blocks the thread while messages are coming in through the stream. Any
     # exceptions that crop up on the thread will be set on the future.
     try:
-        subscription.future.result()
+        # When timeout is unspecified, the result method waits indefinitely.
+        subscription.future.result(timeout=30)
     except Exception as e:
         print(
             'Listening for messages on {} threw an Exception: {}.'.format(
                 subscription_name, e))
-        raise
     # [END pubsub_subscriber_error_listener]