[SBC mode] Random errors in macros with 3.5.2

[crpalmer]

My PrusaSlicer start gcode is:

M83          ; Relative Extruder mode
M98 P"/sys/prepare-to-print.g" H{is_extruder_used[0] ? first_layer_temperature[0] : 0} B{is_extruder_used[0] ? first_layer_bed_temperature[0] : 0}
T{initial_tool}

and the macro prepare-to-print.g is:

if exists(param.H) == false or exists(param.B) == false
  echo "Missing required parameter (H and B)"
  M99

var bed_temp = param.B
var probing_temp = min(var.bed_temp, 60)

;echo "Hotend temperatures: ", param.H
;echo "Probing temperature: ", var.probing_temp
;echo "Bed temperature: ", var.bed_temp

M220 S100     ; clear any speed changes
M290 R0 S0    ; clear any baby stepping
M106 S0       ; disable fans

M568 A1 P0 R{param.H} S{param.H}
M190 R{var.probing_temp+10}    ; Wait to get up (or down!) to the right temperature

M561
M98 P"/sys/homexy-if-needed.g"
M401
G28 Z
G32
G32
G28 Z
G29 S1

M98 P"/sys/retractprobe-forced.g"

if var.probing_temp < var.bed_temp
   M140 S{var.bed_temp+10}

M116

Since upgrading to 3.5.2 on one printer and a new deployment of 3.5.2 on another printer, I'm sporatically seeing errors on both printers when this macro is invoked while starting a print. Both printers are running Duet 3 Mini 5+ control boards.

The most common error I get is:

Error: in file prepare-to-print.g line 31: unknown variable 'probing_temp'

where probing_temp is used extensively thoughout the macro and line 31 (I assume really line 30 but reported as 31) is always executed and therefore if it was an error in the macro then it should always report the error. I just recently also saw this warning:

Warning: Macro file has been started on channel File but none was requested

Possibly related to these errors I am getting situations where clicking Pause Print in the web interface hangs and does nothing (a page reload shows the print still running) and when I received the warning, my filament sensor didn't trigger which makes we think that the warning / error is causing RRF to think that the print is not running even though the print is running.

Note that on the machine I upgraded to 3.5.2, the prepare-to-print macro has been running for a long time without any changes without ever reporting an error until version 3.5.2.

Am I doing something incorrect in how I use macros inside of macros? Is something that I'm doing venturing into undefined behaviour? Note that the macro prepare-to-print will invoke the macro homexy-if-needed which will invoke the macro homexy. Prepare-to-print also invokes the macro retractprobe-forced which will invoke the macro retract-probe.

(edit to add that I looked at the 3.5.3-rc.1 changelog and git diff 3.5.2 3.5.3-rc.1 and nothing appears to be related to me)

[dc42]

@crpalmer are you running in standalone or SBC mode?

[crpalmer]

@dc42 sbc for both machines.