Some alternative to Lua, or at least the mainline Lua release?

I'm having a lot of trouble with the lack of documentation (I had to dig and poke around for days to get it working not from the files directly, only for it to stop working again in the same way, all while still having the fix for it), and the lack of an incentive from some of its other users in the D community to make anything newer than 5.1 working (I NEED INTEGER SUPPORT).

Basically I need a relatively lightweight scripting library for my game engine written in D, that isn't a toy language (which doesn't have integer support). Most other scripting libraries lack integer support (even Lua did until 5.4, because yOU CaN JuST uSE rOUnDIng ON youR BaCKeNd) and/or are heavily bloated (I don't want to include 50+MB stuff just because it's trendy to make your scripting language a slow and clunky application language (I'm looking at you, Javascript!)). I'm using D, but it can interface with both C and C++.

I would be fine with Lua, and if I had the time, I'd just reimplement it in D without the godawful and confusing stack method of interaction. But now I have to look for some feasible alternatives.