autogui error in SC 3.11 - 3.12.1

[avdrd]

With SC 3.12.1 it doesn't work at all basically:

SynthDef(\yawn, { arg freq = 499, amp = 0.1; Out.ar(0, amp*SinOsc.ar(freq)).add
x = Synth(\yawn);
x.autogui

gives

ERROR: Message 'at' not understood.
RECEIVER:
   nil
ARGS:
   Integer 0

CALL STACK:
	DoesNotUnderstandError:reportError
		arg this = <instance of DoesNotUnderstandError>
	Nil:handleError
		arg this = nil
		arg error = <instance of DoesNotUnderstandError>
	Thread:handleError
		arg this = <instance of Thread>
		arg error = <instance of DoesNotUnderstandError>
	Object:throw
		arg this = <instance of DoesNotUnderstandError>
	Object:doesNotUnderstand
		arg this = nil
		arg selector = 'at'
		arg args = [*1]
	SynthDefAutogui:initSynthDefAutogui
		arg this = <instance of SynthDefAutogui>
		arg argArray = [*15]
	Synth:autogui
		arg this = <instance of Synth>
		arg rate = 'audio'
		arg closeOnCmdPeriod = true
		arg freeOnClose = false
		arg window = nil
		arg step = 50
		arg hOff = 0
		arg vOff = 0
		arg scopeOn = true
		arg specs = nil
		arg onInit = true
	Interpreter:interpretPrintCmdLine
		arg this = <instance of Interpreter>
		var res = nil
		var func = <instance of Function>
		var code = "x.autogui"
		var doc = nil
		var ideClass = <instance of Meta_ScIDE>
	Process:interpretPrintCmdLine
		arg this = <instance of Main>
^^ ERROR: Message 'at' not understood.
RECEIVER: nil

This error was actually reported by two other people, going as far back as SC 3.11.

• controlSpec warnigs #1 (comment)
• controlSpec warnigs #1 (comment)

Bu they alas confused it a bit with the other issues of warnings printed on this quark's compilation, warnings which are not exactly related to this error.

[avdrd]

I found the error. It tries to do this:

SynthDefStorage.synthDefDict[name.asString][0]

But replicating that

SynthDef(\yawn, { arg freq = 499, amp = 0.1; Out.ar(0, amp*SinOsc.ar(freq) ) }).add 
SynthDefStorage.synthDefDict[\yawn][0] // ok 
// but
SynthDefStorage.synthDefDict[\yawn.asString][0];
// ERROR

So it looks like the conversion to String breaks it. It needs asSymbol in a recent SC.