This time I dont get any error in game, but when I use "Mining drones" (https://mods.factorio.com/mod/Mining_Drones) workers to mine iron they drop coins too.
I think you've to indagate what trigger this effect, because it give a huge advantage to this 2 mods users.
I've tried only iron actually, then I'm not sure if it happen even with others kind of ores.
I will update this thread once I've verified it.

It seems to work with any mined ore.
Then it's a mining event that trigger the coin drop.

Ah yea this will be a clash. Mining drones don't actually mine, they attack an invisible enemy to simulate mining. So my mod is reacting to this killed invisible enemy. I will have a think about how to approach this and other potential similar oddities.

That's the reason I've reported it. :D
Dont worry. Actual game has no way to spend cash, then I'm just collecting them.

handled in new version, couldn't find an elegant way to handle the variation the mining drones introduced, but the fix works.

Wonderful. Nice job. And thanks.