[DefaultAssetLibrary] WARNING: Could not load asset manifest (bytes was null)
[lime.utils.Assets] There is no IMAGE asset with an ID of “assets/bullets.png”
Called normally var bitmapData = Assets.getBitmapData("assets/bullets.png");
Openfl and lime latest git version. Can’t pinpoint when exactly it broke, as I’ve been testing on flash for some time.
Case sensitive? Long shot, but worth a try. 
If you’re using the latest GIT version, try this:
cd openfl
git pull
cd lime
git pull
git submodule init
git submodule update
openfl rebuild tools
openfl rebuild windows -clean
You don’t have to do a clean often on Lime (usually never), but there’s a chance you might have to, depending on how long you have had your GIT directory. Lime also doesn’t change submodules often, but it’s worth checking. Lastly, there were tool changes in order to accompany improvements to asset manifests in Lime, so rebuilding the tools is probably needed.