Error during VP9 bitrate encoding

I get this error during the second pass:
```
[libvpx-vp9 @ 0x55e0931b8f40] Failed to initialize encoder: Invalid parameter
[libvpx-vp9 @ 0x55e0931b8f40] Additional information: rc_twopass_stats_in.buf not set.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!
```

These are the raw commands:

First pass:
`
"/usr/bin/ffmpeg" -y -i "/home/buymymojo/Videos/Source.mkv" -map 0:0 -c:v libvpx-vp9 -pix_fmt yuv420p -row-mt 1 -color_primaries bt709 -color_trc bt709 -colorspace bt709 -passlogfile "/home/buymymojo/.local/share/FastFlix/temp_6f5db49dc2784ff259a69287/pass_log_file_d67079147a92138ce44e" -speed:v 4 -b:v 6000k -quality:v realtime -profile:v 0 -tile-columns:v -1 -tile-rows:v -1 -pass 1 -an -f webm /dev/null
`

Second pass:
`
"/usr/bin/ffmpeg" -y -i "/home/buymymojo/Videos/Source.mkv" -map 0:0 -c:v libvpx-vp9 -pix_fmt yuv420p -row-mt 1 -color_primaries bt709 -color_trc bt709 -colorspace bt709 -passlogfile "/home/buymymojo/.local/share/FastFlix/temp_6f5db49dc2784ff259a69287/pass_log_file_d67079147a92138ce44e" -speed:v 8 -b:v 6000k -quality:v realtime -profile:v 0 -tile-columns:v -1 -tile-rows:v -1 -pass 2 -map_metadata 0 -map_chapters -1 -map 0:1 -metadata:s:1 title="" -metadata:s:1 handler="" -metadata:s:1 language=eng -c:1 libopus -b:1 128k -default_mode infer_no_subs "/home/buymymojo/Videos/Source-fastflix-e7cb.mkv"
`