Problem with PackageManager>>onSystemClassRemoved:

> In porting my partially completed application from Dolphin 3 to 4, I
> find that the running application triggers an assertion in
> PackageManager>>onSystemClassRemoved: when it programmatically removes a
> class.  It looks like pkg is nil when the method below runs and the
> changed collection doesn't include nil, apparently.  The removed class
> is uncommitted and was also loaded programmatically.
>
> Some methods further up the call stack have some #todo's left and this
> might be one.  I'm adding a check for nil here without knowing if that's
> the real solution.  Heads up.
>
> Keith Alcock
>
> !PackageManager methodsFor!
>
> onSystemClassRemoved: aClass
>  "Private - React to aClass being removed from the Smalltalk system.
>  Ensure that none of the packages held by the receiver refer to aClass
>  or its methods now it has departed."
>
>  self isProcessingEvents ifTrue: [ | changed pkg |
>   pkg := packagedGlobals removeKey: aClass name ifAbsent: [].
>   "We must inform all packages, not just the package owning the class,
>    in case any other packages include loose methods of the class. In
> case
>   they do we empty our loose method cache."
>   self forgetLooseMethods.
>   changed := self packages select: [:aPackage | aPackage onClassRemoved:
> aClass].
>   self assert: [looseMethods isNil].
>   "Modification here."
>   pkg notNil ifTrue: [
>    self assert: [
>     changed includes: pkg.
>    ].
>   ].
>   changed do: [:aPackage | aPackage ownedChanged].
>   self resetPrerequisites].
> ! !