Reading of uninitialized local variables is broken

[smarr]

Reading of uninitialized variables in methods is currently broken.

The following test fails with an assertion, because the read evaluates to null:

class Test usingPlatform: platform = Value ()(
  protected foo = (
    | a |
    a println.
    a := 1.
    a println.
  )

  public main: args = (
    foo.
    foo.
    ^ 0
  )
)

A fix could be:

diff --git a/src/som/compiler/MethodBuilder.java b/src/som/compiler/MethodBuilder.java
index 1598a2b..20e8757 100644
--- a/src/som/compiler/MethodBuilder.java
+++ b/src/som/compiler/MethodBuilder.java
@@ -101,7 +102,8 @@ public final class MethodBuilder {
     MethodScope outer = (outerBuilder != null)
         ? outerBuilder.getCurrentMethodScope()
         : null;
-    this.currentScope   = new MethodScope(new FrameDescriptor(), outer, clsScope);
+    assert Nil.nilObject != null;
+    this.currentScope   = new MethodScope(new FrameDescriptor(Nil.nilObject), outer, clsScope);

     accessesVariablesOfOuterScope = false;
     throwsNonLocalReturn          = false;