A new version of System was added to project The Inbox:
http://source.squeak.org/inbox/System-kfr.1161.mcz

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

Name: System-kfr.1161
Author: kfr
Time: 4 June 2020, 11:05:51.49313 pm
UUID: 38776d4a-508a-7044-ab72-4cb34ceaceea
Ancestors: System-mt.1160

Return nil instead of opening pre debugger

=============== Diff against System-mt.1160 ===============

Item was changed:
  ----- Method: StandardFileStream class>>fileExistsUserHandling:ifDebug: (in category '*System-Files-error handling') -----
  fileExistsUserHandling: fullFileName ifDebug: debugBlock
  	| dir localName choice newName newFullFileName |
  	dir := FileDirectory forFileName: fullFileName.
  	localName := FileDirectory localNameFor: fullFileName.
  	choice := (UIManager default 
  		chooseFrom: #('overwrite that file' 'append (risky!!!!)' 'choose another name' 'debug' 'cancel')
  		title: localName, ' already exists.').
  
  	choice = 1 ifTrue: [
  		dir deleteFileNamed: localName
  			ifAbsent: [self error: 'Could not delete the old version of that file'].
  		^ self new open: fullFileName forWrite: true].
  
  	choice = 2 ifTrue: [
  		^ (self new open: fullFileName forWrite: true) setToEnd].
  
  	choice = 3 ifTrue: [
  		newName := UIManager default request: 'Enter a new file name' initialAnswer: fullFileName.
  		newFullFileName := self fullName: newName.
  		^ self newFileNamed: newFullFileName].
  
  	choice = 4 ifTrue: [^ debugBlock value].
  
+ 	choice = 5 ifTrue: [^ nil].!
- 	self error: 'Please close this to abort file opening'!