M502 returns array index error

[OwenD]

Just noticed a curiosity.
If I run
M98 P"0:/sys/config.g"
I get no errors.

However if I run M502 I get n array index out of bounds error for this code

;load config for filament
if move.extruders[state.currentTool].filament=""
	echo "No filament loaded.  Cold extrude & retract set to defaults"
	M302 S190 R110 ; Allow extrusion starting from 190°C and retractions already from 110°C (defaults)
	set global.LoadedFilament="No_Filament"
else
	set global.LoadedFilament=move.extruders[state.currentTool].filament ; set the variable to the currently loaded filament
	echo "Loading config for " ^ global.LoadedFilament ^ " filament"
	M703 ; if a filament is loaded, set all the heats and speeds for it by loading config.g
G4 P10

Attached is the complete config.g

It's not really causing me a problem, but I can't figure out why the results differ.
If I put an echo command it resolves correctly.

config.g

[dc42]

@owend when M502 is run, T commands in config.g are not executed. I expect this causes state.currentTool to be -1 in the code you posted.

[OwenD]

@dc42
That's what I initially thought, but if I put
echo state.currentTool on the line above it returns 0
Yet if I hard code the extruder object to zero it stops complaining, so it must be -1 somewhere in code/memory

I'll mark as solved with a

EDIT: 10 seconds after I posted it hit me.
It's because the heater was turned off using M568 A0
This has the effect of the tool index being -1 despite T0 being selected