In the file Compile.Lua the function "isTable()" is called in line 511. This function will be defined later in the same file (line 522), which can lead to an error. Furthermore, there seem to be OvaleData.spellInfos (in my case spellID 165822) that have neither the field stacking nor max_stacks defined.

Therefore I have extended line 509 as follows:
isStacking = si and si.stacking and si.max_stacks and (si.stacking == 1 or si.max_stacks > 0)

Something else: "define(death_strike 278223)" should use spellId 49998 and it needs "runicpower=-45".
Are the *_spells.lua autogenerated? I am asking, because spell 278223 doesnt need any runicpower.

Yes everything between

// THIS PART OF THIS FILE IS AUTOMATICALLY GENERATED
// ANY CHANGES MADE BELOW THIS POINT WILL BE LOST

//END

is autogenerated