VIDEOJS: ERROR: TypeError: "this.player(...) is null"

Getting this error a lot on some files when attempting to play them, the video doesn't play. v0.3.1 running in Docker, Firefox 71.

VIDEOJS: ERROR: TypeError: "this.player(...) is null"
    update videojs-http-source-selector.es.js:70
    dispatcher video.es.js:1901
    Se video.es.js:2039
    trigger video.es.js:2448
    dn videojs-http-streaming.es.js:17590
    value videojs-http-streaming.es.js:18223
    dispatcher video.es.js:1901
    Se video.es.js:2039
    trigger video.es.js:2448
    value videojs-http-streaming.es.js:9995
    value videojs-http-streaming.es.js:16095
    enabled videojs-http-streaming.es.js:16863
    set videojs-contrib-quality-levels.es.js:80
    handleClick videojs-http-source-selector.es.js:58
    dispatcher video.es.js:1901
video.es.js:76:47