webhooks.patch

diff --git klippy/webhooks.py klippy/webhooks.py
index 458a77b1..b6708232 100644
--- klippy/webhooks.py
+++ klippy/webhooks.py
@@ -311,15 +311,23 @@ class ClientConnection:
             return
         self.send(result)
 
-    def send(self, data):
+    def _safe_dumps(self, data):
         try:
-            jmsg = json.dumps(data, separators=(",", ":"))
-            self.send_buffer += jmsg.encode() + b"\x03"
+            return json.dumps(data, separators=(",", ":"))
         except (TypeError, ValueError) as e:
-            msg = "json encoding error: %s" % (str(e),)
+            msg = "json encoding error: %s, data: %s" % (str(e),str(data))
             logging.exception(msg)
+            logging.info("DATA DUMP:")
+            for k,v in data.items():
+                logging.info(f"  {k} -> {v} ({type(v)})")
             self.printer.invoke_shutdown(msg)
+            return None
+
+    def send(self, data):
+        jmsg = self._safe_dumps(data)
+        if jmsg is None:
             return
+        self.send_buffer += jmsg.encode() + b"\x03"
         if not self.is_blocking:
             self._do_send()