Could you apply following patch:

Index: mods/zk-lib_0.12.4/experimental/lazyAPI.lua
MY DESCRIPTION: mods conflict fix: aai-vehicles-ironclad_0.6.6.zip
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/mods/zk-lib_0.12.4/experimental/lazyAPI.lua b/mods/zk-lib_0.12.4/experimental/lazyAPI.lua
--- a/mods/zk-lib_0.12.4/experimental/lazyAPI.lua   (revision 978cb15dfbf6032925fb572bb31d74ad5a13d3cd)
+++ b/mods/zk-lib_0.12.4/experimental/lazyAPI.lua   (date 1675596936355)
@@ -1038,9 +1038,12 @@
                data_raw[_type] = {}
                lazyAPI.deleted_data[_type] = lazyAPI.deleted_data[_type] or {}
            end
-           local prev_instance = data_raw[_type][name]
+           local prev_instance = data_raw[_type] and data_raw[_type][name]
            -- Perhaps it should verify this case later instead
            if prev_instance and prev_instance ~= prototype then
+               if not lazyAPI.deleted_data[_type] then
+                   lazyAPI.deleted_data[_type] = {}
+               end
                lazyAPI.deleted_data[_type][prototype.name] = prototype -- TODO: recheck, perhaps I should use a metamethod instead

                local event_data = {prototype = prototype, prev_instance = prev_instance}
@@ -1067,7 +1070,7 @@
            local name = prototype.name
            local is_added = (data_raw[prototype_type][name] == prototype)
            if is_added then
-               local removed_prot = lazyAPI.deleted_data[prototype_type][name]
+               local removed_prot = lazyAPI.deleted_data[prototype_type] and lazyAPI.deleted_data[prototype_type][name]
                if removed_prot == prot then
                    lazyAPI.deleted_data[prototype_type][name] = nil
                end

or just fix issues above with your way

Um, does zk-lib_0.12.4 crash with aai-vehicles-ironclad_0.6.6?

hmm, it was issue in 0.12.0-3 if I remember, I need check it on pure 0.12.4

I had a similar bug report for <0.12.2, but I fixed it in 0.12.2

looks like it fixed, at least it starts the factorio app with a full pack of mods and it loads old saves without a crash.
Let me return to this patch/topic if it'll lead to this issue in the game

Well, you could do that and the issue is more broadly. data.raw doesn't have some types by default, but, apparently, it supports some undocumented types.

or someone messing around