More simplifications.

Now that exception handlers are outside of the fast path, we can just use a block.

src/MethodProxies/MpCannotInstall.class.st

@@ -1,3 +1,7 @@
+"
+I'm an exception raised when a proxy cannot be installed.
+This usually happens when the wrapped method is a very special method whose instrumentation could break the system.
+"
 Class {
 	#name : #MpCannotInstall,
 	#superclass : #Error,

src/MethodProxies/MpHiddenSelector.class.st

@@ -1,3 +1,10 @@
+"
+I represent a selector that is hidden for the user, used to install hidden methods in method dictionaries.
+I'm not a string, so I cannot be typed, avoiding potential conflicts.
+
+I'm used as key of the original method wrapped by proxies, to ensure this wrapped method can be called using myself as selector.
+Check my usages during proxy installation.
+"
 Class {
 	#name : #MpHiddenSelector,
 	#superclass : #Object,

src/MethodProxies/MpMethodProxy.class.st

@@ -1157,8 +1157,22 @@ MpMethodProxy >> install [
 		(proxyMethod hasPragmaNamed: #noInstrumentation) ifTrue: [
 			^ MpCannotInstall signalWith: self ].
 
-		deactivator := MpProxyInstrumentationDeactivator new.
-		deactivator handler: handler.
+		deactivator := [ "Execution handler for the slow path. An exception or a non local return happened during proxy execution"
+			| wasMeta trapContext |
+
+			"Jump to the meta level (to avoid meta-recursions) to observe if the handler was in a meta level, marked by the wasMeta flag.
+			During the meta-jump call the handler to tell there was an unwind.
+			"
+			thisProcess shiftLevelUp.
+			trapContext := thisContext findContextSuchThat: [ :ctx | ctx isUnwindContext ].
+			wasMeta := trapContext tempNamed: 'wasMeta'.
+			handler aboutToReturnWithReceiver: trapContext receiver arguments: trapContext arguments.
+			thisProcess shiftLevelDown.
+
+			"If the handler was in a meta-state (i.e., the exception or non-local return happened in the handler), shift it back to the base level before returning.
+			Otherwise, we were already in the base level and we need to do nothing!"
+			wasMeta ifTrue: [ thisProcess shiftLevelDown ].
+	 	].
 
 		newTrap := self trapMethodPrototype copy.
 		trapSelector := newTrap selector.