splitmuxsink: Fix assertion failure on set_property() when unsetting sink or muxer
GValue might have null object.
(gst-inspect-1.0:10304): GStreamer-CRITICAL ... gst_object_ref_sink: assertion 'object != NULL' failed
Edited by Tim-Philipp Müller
GValue might have null object.
(gst-inspect-1.0:10304): GStreamer-CRITICAL ... gst_object_ref_sink: assertion 'object != NULL' failed