vimeo.lua: fix error case

(cherry picked from commit 2e5c5442c8a604bd4446dc64a84f82b2426af80f)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

share/lua/playlist/vimeo.lua

@@ -96,8 +96,8 @@ function parse()
     end
 
     if not codec then
-        vlc.msg.warn("unable to find codec info")
-        return nil
+        vlc.msg.err("unable to find codec info")
+        return {}
     end
 
     if ishd and ( not height or prefres < 0 or prefres >= tonumber(height) ) then