Network initialization for the Pushbullet backend should be done in the run method.

Network errors in the constructor cause the whole application to fail.
Better to do the initialization in the run method with retries.

platypush/backend/pushbullet/__init__.py

@@ -1,5 +1,6 @@
 import json
 import time
+from typing import Optional
 
 from platypush.backend import Backend
 from platypush.message.event.pushbullet import PushbulletEvent
@@ -24,34 +25,30 @@ class PushbulletBackend(Backend):
         * **pushbullet.py** (``pip install git+https://github.com/rbrcsk/pushbullet.py``)
     """
 
-    def __init__(self, token, device='Platypush', proxy_host=None,
-                 proxy_port=None, **kwargs):
+    def __init__(self, token: str, device: str = 'Platypush', proxy_host: Optional[str] = None,
+                 proxy_port: Optional[int] = None, **kwargs):
         """
-        :param token: Your Pushbullet API token, see
-            https://docs.pushbullet.com/#authentication
-        :type token: str
-
+        :param token: Your Pushbullet API token, see https://docs.pushbullet.com/#authentication
         :param device: Name of the virtual device for Platypush (default: Platypush)
-        :type device: str
-
         :param proxy_host: HTTP proxy host (default: None)
-        :type proxy_host: str
-
         :param proxy_port: HTTP proxy port (default: None)
-        :type proxy_port: int
         """
-
-        # noinspection PyPackageRequirements
-        from pushbullet import Pushbullet
         super().__init__(**kwargs)
 
         self.token = token
         self.device_name = device
         self.proxy_host = proxy_host
         self.proxy_port = proxy_port
-        self.pb = Pushbullet(token)
+        self.device = None
+        self.pb_device_id = None
+        self.pb = None
         self.listener = None
 
+    def _initialize(self):
+        # noinspection PyPackageRequirements
+        from pushbullet import Pushbullet
+        self.pb = Pushbullet(self.token)
+
         # noinspection PyBroadException
         try:
             self.device = self.pb.get_device(self.device_name)
@@ -135,6 +132,16 @@ class PushbulletBackend(Backend):
         # noinspection PyPackageRequirements
         from pushbullet import Listener
         super().run()
+        initialized = False
+
+        while not initialized:
+            try:
+                self._initialize()
+                initialized = True
+            except Exception as e:
+                self.logger.exception(e)
+                self.logger.error('Pushbullet initialization error: {}'.format(str(e)))
+                time.sleep(30)
 
         self.logger.info('Initialized Pushbullet backend - device_id: {}'
                          .format(self.device_name))