prefilter == 1 and 2 both yield error: "I don't know what 'Lum' means"

[JohnstonJ]

Describe the bug
The SMDegrain filter crashes with error:

To Reproduce

This simple filter statement seems adequate to trigger it:

SMDegrain(prefilter=1)

Prefilter 2 is also broken in the same way.

Expected behavior

The prefilter should be run and applied as part of image processing.

System:

• OS: Windows 10
• Version: files from https://github.com/Dogway/Avisynth-Scripts/tree/31459ff64fa39a3ea00b5cabb288e980b57a5b00 running with AviSynthPlus_3.7.3_20230715-filesonly

Additional context

At

Avisynth-Scripts/SMDegrain/SMDegrain.avsi

Lines 320 to 321 in 31459ff

	(prefilter== 1) ? pref.ex_MinBlur(1,Chr,isInter ? """ex_Median(mode="horizontal" ,Y=Lum,UV=uv)""" : "median",Y=Lum) : \
	(prefilter== 2) ? pref.ex_MinBlur(2,Chr,isInter ? """ex_Median(mode="horizontalS",Y=Lum,UV=uv)""" : "median",Y=Lum) : \

I notice that a special string is passed to ex_MinBlur containing the named parameter Y=Lum that is to be passed to ex_Median.

Later on, it is passed to Eval, for evaluation inside the ex_MinBlur function. However, that function does not have any variable named Lum in it, and thus I think that is probably the source of the error.

Avisynth-Scripts/SMDegrain/SMDegrain.avsi

Line 779 in 31459ff

(rg4v) ? clp.removegrain(rg27y,rg27) : Eval("clp."+blurstr+"")

If I change the ex_Median call to read """ex_Median(mode="horizontal" ,Y=Y,UV=uv)""", then the SMDegrain filter will run successfully, but I am not familiar enough with this filter to know whether the results are as expected or not.