I don't think the code handling for images/videos (non-thumbnails) needed to be modified if uploadPromises is only scoped to this try / catch block, since we'll need to have access to thumbnailResult in the future anyways.

We can just create a variable for it outside where uploadResult is declared, then it's clearer to me what each step means since we explicitly set the inner if statement's result to uploadThumbnailResult. This is a minor change, but it saves some lines so I figured I'd submit it to see if you think it's more concise or clear.

Tried doing this in a suggested edit, but it was really hard to see because it was so big:

let uploadExceptionMessage,
  uploadResult,
  thumbnailUploadResult,
  mediaMissionResult;
try {
  uploadResult = await this.props.uploadMultimedia(
    { uri: uploadURI, name: filename, type: mime },
    {
      ...processedMedia.dimensions,
      loop:
        processedMedia.mediaType === 'video'
          ? processedMedia.loop
          : undefined,
    },
    {
      onProgress: (percent: number) =>
        this.setProgress(
          localMessageID,
          localMediaID,
          'uploading',
          percent,
        ),
      uploadBlob: this.uploadBlob,
    },
  );

  if (processedMedia.mediaType === 'video') {
    thumbnailUploadResult = await this.props.uploadMultimedia(
      {
        uri: processedMedia.uploadThumbnailURI,
        name: replaceExtension(`thumb${filename}`, 'jpg'),
        type: 'image/jpeg',
      },
      { ...processedMedia.dimensions, loop: false },
      { uploadBlob: this.uploadBlob },
    );
  }
  mediaMissionResult = { success: true };
}

It looks like currently, in the database, every piece of media has a loop: false property in the extra column, including images.

Is setting loop to undefined having an effect if loop: false is showing up anyways? Why can't we just set loop to processedMedia.loop? (I know it's because loop should only exist for videos, but what is the point of setting it to undefined if it shows up anyways.)

I tested this code without replaceExtension on this line and instead wrote filename and it seems it works (see the filename column):

The only difference is the thumb isn't prefixed to the filename column, but that can be fixed easily.

Weird that Prettier wants this on separate lines...it's also ok with it on the same line. I think this looks better?

Why don't we pass the onProgress function here, as we do above?

Ah I see. By removing the awaits for each upload result we can decrease some amount of blocking and instead parallelize the uploads. That's pretty smart!

Ah I worded this badly. I know loop shouldn't be set for images because only videos can loop. I'm saying we should determine where loop is getting set for images, because right now setting it to undefined is not having the intended effect (I think). An undefined prop shouldn't show up in the object in extra, right? And storing the loop property for images is wasteful and sort of inaccurate, which is why we are setting it to undefined in the first place. But it's not doing anything, so that should be figured out.

Yup, the filename for the thumbnail is a JPG when it enters here.

I'll take a look to see if replaceExtension is really necessary or we can just prepend thumb

Will you update that in this diff or create a separate diff? Requesting changes for a response to this, other than that looks good.

No...Prettier suggested to put it on one line when I originally wrote the code and hit save. I was noting that it's weird it's also ok with it on separate lines since it auto-formatted it to one line for me. To me, it looks better on one line since that's how it's formatted before (line 660) / takes up less lines.

Ohh, that does make sense.