IndexError: list index out of range

[vinay5018]

WARNING: You have requested multiple formats but ffmpeg or avconv are not installed. The formats won't be merged.
ERROR:pyrogram.client.ext.dispatcher:list index out of range
Traceback (most recent call last):
File "/usr/local/lib/python3.8/dist-packages/pyrogram/client/ext/dispatcher.py", line 204, in update_worker
await handler.callback(self.client, *args)
File "/home/xxxx/github/Youtube-Downloader-Bot/plugins/youtube_callback_data.py", line 114, in catch_youtube_dldata
filename = await downloadvideocli(video_command)
File "/home/xxxx/github/Youtube-Downloader-Bot/helper/ytdlfunc.py", line 63, in downloadvideocli
filename = t_response.split("Merging formats into")[-1].split('"')[1]
IndexError: list index out of range

I have ffmpeg is install still getting this error any idea