handle null extra heartbeats

wakatime/compat.py

@@ -96,5 +96,5 @@ except ImportError:  # pragma: nocover
 
 try:
     from .packages import simplejson as json
-except (ImportError, SyntaxError):
+except (ImportError, SyntaxError):  # pragma: nocover
     import json

wakatime/configs.py

@@ -21,7 +21,7 @@ from .constants import CONFIG_FILE_PARSE_ERROR
 
 try:
     import configparser
-except ImportError:
+except ImportError:  # pragma: nocover
     from .packages import configparser
 
 

wakatime/heartbeat.py

@@ -41,6 +41,10 @@ class Heartbeat(object):
     user_agent = None
 
     def __init__(self, data, args, configs, _clone=None):
+        if not data:
+            self.skip = u('Skipping because heartbeat data is missing.')
+            return
+
         self.args = args
         self.configs = configs
 
@@ -91,7 +95,6 @@ class Heartbeat(object):
         data = self.dict()
         data.update(attrs)
         heartbeat = Heartbeat(data, self.args, self.configs, _clone=True)
-        heartbeat.skip = self.skip
         return heartbeat
 
     def sanitize(self):