Get URL for img src not working

[arj03]

I'm using this library like this:

      const mutableAccess = require('random-access-idb-mutable-file')
      mutableAccess.mount({}).then((requestFile) => {
        var f = requestFile(filepath)
        f.open((err) => {
          f.file.getFile().then((fileObj) => {
            cb(null, URL.createObjectURL(fileObj))
          })
        })
      })

I get an URL like blob:null/ae825970-3f3a-4834-bc5c-ada3789b83c5 from createObjectURL, but if I try to use this as img src=, the blob is not properly loaded. Any idea how to go about this?

Thanks