internal error when referencing cell before initialization

[alandonovan]

$ starlark
Welcome to Starlark (go.starlark.net)
>>> def f():
...   def g(): return x
...   if False:
...     x = 1
...   return g()
... 
>>> f()
Traceback (most recent call last):
  <stdin>:1:2: in <expr>
  <stdin>:5:11: in f
  <stdin>:2:19: in g
Error: internal error: nil (not None) returned from <function g>

[alandonovan]

Related:

$ starlark
Welcome to Starlark (go.starlark.net)
>>> def f():
...   def g(): return x
...   if False:
...    x = 1
...   return x
... 
>>> f()
Traceback (most recent call last):
  <stdin>:1:2: in <expr>
  <stdin>:5:10: in f
Error: internal error: nil (not None) returned from <function f>