From b96935eb4fa3a3c2a0033ced973c7913b3e68891 Mon Sep 17 00:00:00 2001
From: Max Leske <250711+theseion@users.noreply.github.com>
Date: Sat, 18 Oct 2025 14:39:28 +0200
Subject: [PATCH 1/2] fix: make
 OnlineSourceDebugInfo>>#readVariableNamed:fromContext: work with dead
 contexts

Use `#currentPC` instead of `pc` to access the PC of the context to prevent errors
on dead contexts, where `pc` is `nil`.

fixes #18718
---
 src/DebugInfo-Tests/DebugInfoTest.class.st   | 18 ++++++++++++++++++
 src/DebugInfo/OnlineSourceDebugInfo.class.st |  2 +-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/DebugInfo-Tests/DebugInfoTest.class.st b/src/DebugInfo-Tests/DebugInfoTest.class.st
index 2772e4aca83..9f6d113bc56 100644
--- a/src/DebugInfo-Tests/DebugInfoTest.class.st
+++ b/src/DebugInfo-Tests/DebugInfoTest.class.st
@@ -825,6 +825,24 @@ DebugInfoTest >> testReadLocalMethodTemporaryVariable [
 		equals: contextWithArguments
 ]
 
+{ #category : 'tests - read variables' }
+DebugInfoTest >> testReadLocalMethodTemporaryVariableFromDeadContext [
+
+	| debugInfo contextWithArguments |
+	contextWithArguments := thisContext copy
+		pc: nil;
+		yourself.
+	self assert: contextWithArguments isDead.
+	debugInfo := self newDebugInfoFor: contextWithArguments method.
+
+	self
+		shouldnt: [
+			debugInfo
+				 readVariableNamed: #contextWithArguments
+				 fromContext: contextWithArguments ]
+		raise: MessageNotUnderstood
+]
+
 { #category : 'tests - read variables' }
 DebugInfoTest >> testReadLocalOptimizedBlockArgumentVariable [
 
diff --git a/src/DebugInfo/OnlineSourceDebugInfo.class.st b/src/DebugInfo/OnlineSourceDebugInfo.class.st
index 1eb93e5eb38..1810d23d0b3 100644
--- a/src/DebugInfo/OnlineSourceDebugInfo.class.st
+++ b/src/DebugInfo/OnlineSourceDebugInfo.class.st
@@ -250,7 +250,7 @@ OnlineSourceDebugInfo >> rangeForPC: aPC [
 { #category : 'api' }
 OnlineSourceDebugInfo >> readVariableNamed: aName fromContext: aContext [
 
-	^ (self debugScopeAt: aContext pc) readVariableNamed: aName fromContext: aContext
+	^ (self debugScopeAt: aContext currentPC) readVariableNamed: aName fromContext: aContext
 ]
 
 { #category : 'api' }

From aa5fd2c4b542a3cc594596e549faca94664f4d7a Mon Sep 17 00:00:00 2001
From: Max Leske <250711+theseion@users.noreply.github.com>
Date: Tue, 11 Nov 2025 07:13:21 +0100
Subject: [PATCH 2/2] Apply review suggestions

Co-authored-by: Guille Polito <guillermopolito@gmail.com>
---
 src/DebugInfo/OnlineSourceDebugInfo.class.st | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/DebugInfo/OnlineSourceDebugInfo.class.st b/src/DebugInfo/OnlineSourceDebugInfo.class.st
index 1810d23d0b3..b0d400fcb0b 100644
--- a/src/DebugInfo/OnlineSourceDebugInfo.class.st
+++ b/src/DebugInfo/OnlineSourceDebugInfo.class.st
@@ -250,7 +250,11 @@ OnlineSourceDebugInfo >> rangeForPC: aPC [
 { #category : 'api' }
 OnlineSourceDebugInfo >> readVariableNamed: aName fromContext: aContext [
 
-	^ (self debugScopeAt: aContext currentPC) readVariableNamed: aName fromContext: aContext
+    | currentPC |
+    "If the context is dead (pc = nil) then we really cannot know how to interpret the temp slots, as it could have been killed in any state.
+    For backwards compatibility, assume that the dead context has all the temps available at the beginning of the method -- i.e., at its initial PC"
+    currentPC := aContext pc ifNil: [ compiledCode initialPC ].
+	^ (self debugScopeAt: currentPC) readVariableNamed: aName fromContext: aContext
 ]
 
 { #category : 'api' }