Previously, if an operation failed, we set the result to "null".
However, this was a mistake. Setting the result at all assumes success.
Instead, we need to set an exception so the ListenableFuture knows that
the operation failed.
A variety of improvements to the image editor, such as:
- New, fullscreen styling
- Smoother lines
- Better text and sticker handling
- Improved color picker with a history pallette
- New highlighter tool
