fix: ensure clen is a string

fixes clipious playback

ythdd_inv_tl.py

@@ -279,6 +279,10 @@ def rebuildFormatsFromYtdlpApi(ydata: dict):
 		newRow[           "clen"] = safeTraverse(params, ["clen"], default=safeTraverse(stream, ["filesize"], default="0"))
 		newRow[            "lmt"] = safeTraverse(params,  ["lmt"], default="0")
 
+		if newRow["clen"] is None:
+			# for clipious sake which expects a string
+			newRow["clen"] = "0"
+
 		newRow[ "projectionType"] = "RECTANGULAR" # clipious requires this to be mentioned explicitly and cannot be nulled
 		newRow[      "container"] = safeTraverse(stream, ["ext"], default="unknown_container")
 		newRow[       "encoding"] = safeTraverse(invidious_formats.FORMATS, [int("0" + newRow["itag"].split("-")[0]), "ext"], default="unknown_encoding") # not sure this split is necessary