GESTimelineFileSource: Check uri at _new()
GESTimelineFileSource: Check uri at _new()

Check if uri is valid before creating a new object in
ges_timeline_filesource_new()

pitivi/gst-editing-services,cfoch/ges,cfoch/ges,freesteph/gst-editing-services,MathieuDuponchelle/PitiviGes,cfoch/gst-editing-services,MathieuDuponchelle/PitiviGes,MathieuDuponchelle/PitiviGes,luisbg/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,volodymyrrudyi/gst-editing-services,freesteph/gst-editing-services,ahmedammar/platform_external_gst_editing_services,pitivi/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,cfoch/ges,ahmedammar/platform_external_gst_editing_services,freesteph/gst-editing-services,volodymyrrudyi/gst-editing-services,luisbg/gst-editing-services,cfoch/ges,MathieuDuponchelle/PitiviGes,volodymyrrudyi/gst-editing-services,cfoch/gst-editing-services