dbus-pcap: Track method call error responses

DBus uses a different type value in the fixed header for error responses
vs method call returns, despite the fact that the response is returning
an error. Avoid confusion by tracking the error case as well.

Change-Id: Icaa1492db5ded0f95801fdefcd0fecc72627fbfe
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/dbus-pcap/dbus-pcap b/dbus-pcap/dbus-pcap
index 6fb66a0..0d83b9b 100755
--- a/dbus-pcap/dbus-pcap
+++ b/dbus-pcap/dbus-pcap
@@ -435,7 +435,11 @@
                     calls.add(CallEnvelope(cooked.header.fixed.cookie, s.data))
                 yield packet.time, cooked
             elif track_calls:
-                if cooked.header.fixed.type != MessageType.METHOD_RETURN.value:
+                responseTypes = {
+                    MessageType.METHOD_RETURN.value,
+                    MessageType.ERROR.value,
+                }
+                if cooked.header.fixed.type not in responseTypes:
                     continue
                 rs = [
                     f