NullPointerException when attempting to remap

[TwilightFlower]

If you attempt to remap a .java file that is just a package declaration and imports, Mercury will NullPointerException.

[TwilightFlower]

Paste of the stacktrace (with a bunch of irrelevant org.gradle removed), since I forgot to put that in my original post. https://paste.ee/p/D4iSO

[TwilightFlower]

Actually, this seems to be happening with that file removed, as well. Not sure what this could be in that case. Different file (this one with a class definition), but the stacktrace is the same.

[jamierocks]

For reference the file is CloudRenderer from Minecraft Forge, where the entire class is commented out.

[ramidzkh]

For me this doesn't throw any errors, but it does move the file to the root package instead