SET_PRESSURE_ADVANCE should account for single_extruder_multi_material

[AlejandroRivera]

In Klipper, when using a single extruder MMU setup, if the pressure advance value for different filaments are used, the gcode generated when slicing includes the GCODE SET_PRESSURE_ADVANCE [...] EXTRUDER=extruderX which causes errors in Klipper since the machine won't recognize different extruders other than the single/default extruder.

As a workaround, i found out you can use the extruder name to set it to extruder in all the extruders so this name will be used instead of the extruder{1-N} value.

[legend069]

With your setup does this variable return a empty/null value or a 1 ?

this->config.single_extruder_multi_material.value

[supermerill]

It's possible that a printer have a single nozzle and multiple extruders.
But it's true that's it's more common to only have one.
So I propose to remove the "EXTRUDER=xx" arg only for one-extruder-mmu when there is no extruder name.