It's gone to Undeclared.

If you do

	Undeclared removeUnreferencedKeys; inspect

you'll see it.

When you remove a *class* variable that is still used by code, you get a
dialog asking you if it is OK to move it to Undeclared.

But you don't see that prompt with an instance variable.

If you select that variable name in your code and choose 'explain' from
the context menu, it should explain where it went.

alpha "is an undeclared variable."
SystemNavigation browseAllCallsOn: (Undeclared associationAt: #alpha).

Unfortunately, this explanation of how to see it is wrong. It should be

SystemNavigation new browseAllCallsOn: (Undeclared associationAt:
#alpha).