Trying to add a block I get this crash
here is my script:
{"data":
[
{
"name": "ambientStone",
"harvestLevel": 3,
"hardness": 0.3f,
"toolType": "pickaxe"
}
]
}

if still having this issue remove the f on hardness

Ah, thanks.
But it turns out that there is a larger issue that all blocks need a model file, so that needs to be added before it is really usable.