Christoph Thiede uploaded a new version of System to project The Trunk:
http://source.squeak.org/trunk/System-ct.1268.mcz

==================== Summary ====================

Name: System-ct.1268
Author: ct
Time: 16 December 2021, 8:26:37.797363 pm
UUID: 64f5b0b5-a5fa-d548-8ccb-35ff04070fdc
Ancestors: System-mt.1266

Fixes regression in SmalltalkImage >> #vmParameterAt:ifAbsent: introduced via System-dtl.1261 (treat nil as an absent parameter). Cause: Unconditionally evaluated block argument with non-local return.

As a consequence of this fix, "Processor preemptedProcess" and DebuggerTests >> test01UserInterrupt should work again. =)

See: http://lists.squeakfoundation.org/pipermail/squeak-dev/2021-December/217662.html

=============== Diff against System-mt.1266 ===============

Item was changed:
  ----- Method: SmalltalkImage>>vmParameterAt:ifAbsent: (in category 'vm parameters') -----
  vmParameterAt: parameterIndex ifAbsent: defaultValueOrBlock
  	"Answer a VM parameter or defaultValueOrBlock value if out of range
  	or if the VM does not provide a value for this parameter. A VM parameter
  	is typically numeric or boolean, and if not implemented will be nil."
  	^ [(self vmParameterAt: parameterIndex)
+ 			ifNil: [^ defaultValueOrBlock value]]
- 			ifNil: defaultValueOrBlock value]
  		on: Error
  		do: [defaultValueOrBlock value]!