i get this message when trying to downgrade items with the prismatic quality (different mod) don't know whether it is from this one or prismatic quality
gonna post it there too

The mod Quality Down-Binning (0.4.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event quality-down-binning::on_nth_tick(1)
quality-down-binning/control.lua:79: attempt to compare number with nil
stack traceback:
quality-down-binning/control.lua:79: in function <quality-down-binning/control.lua:59>

This mod currently uses a hard-coded list of the base game qualities, so it's definitely this one.

I'll consider adding dynamic down-binner generation to support modded quality levels. For now, I've added a fail-safe check in 0.5.0 that will make down-binners have no effect on modded quality levels, which will at least prevent crashes.

any way to add the modded quality?
if only to be able to make the rocket

nvm did it myself, (it's level 10)

I've made a fix for mod qualities here for myself. I borrowed some of the code from the mod
"Mega Black Market" by ZeroAinz.
You can use it if you're interested.

local quality_level = {}
local function fill_quality_type()
for name, proto in pairs(prototypes.quality) do
if quality_level[proto.name] == nil then
quality_level[proto.name] = proto.level
end
end
end
fill_quality_type()