Error occurs when Titanium, Krastorio 2 Spaced Out, and Planet Rubia are all enabled.
I couldn't figure out which mod was causing it, so I decided to report it to your mod, which is listed on the Factorio error screen.

bztitanium/data-util.lua:1899: bad argument #1 of 2 to 'pairs' (table expected, got nil)
stack traceback:
[C]: in function 'pairs'
bztitanium/data-util.lua:1899: in function 'redo_recycling'
bztitanium/data-updates.lua:10: in main chunk

4.637 Loading mod bztitanium 2.0.25 (data-updates.lua)
4.650 Error ModManager.cpp:1758: MOD "bztitanium" の読み込みに失敗しました: bztitanium/data-util.lua:1899: bad argument #1 of 2 to 'pairs' (table expected, got nil)
stack traceback:
[C]: in function 'pairs'
bztitanium/data-util.lua:1899: in function 'redo_recycling'
bztitanium/data-updates.lua:10: in main chunk
4.683 Loading mod core 0.0.0 (data.lua)
4.749 Checksum for core: 1117214423
4.777 Error ModManager.cpp:1758: Error in assignID: recipe-category with name 'recycling' does not exist.

All mods that use the function redo_recycling will have the same error. (Silica & Silicon, Lead, etc.)

I was able to fix this mod on my side by making the following line change:

in bztitanium/data-util.lua:1899:
Old Line: for _, product in pairs(recipe.results) do
New line:for _, product in pairs(recipe.results or {}) do

Please implement this sort of fix or related.

Hi apologies for the delay on this. Thanks for the detailed bug report, and thanks for the suggested fix.

I will have an update of all my current mods that do this out very soon.