Make body optional

homeassistant/components/webhook.py

@@ -3,6 +3,7 @@
 For more details about this component, please refer to the documentation at
 https://home-assistant.io/components/webhook/
 """
+import json
 import logging
 
 from aiohttp.web import Response
@@ -75,8 +76,9 @@ class WebhookView(HomeAssistantView):
                 'Received message for unregistered webhook %s', webhook_id)
             return Response(status=200)
 
+        body = await request.text()
         try:
-            data = await request.json()
+            data = json.load(body) if body else {}
         except ValueError:
             _LOGGER.warning(
                 'Received webhook %s with invalid JSON', webhook_id)