small bugfix: code generation for nil closures

todo.txt

@@ -9,15 +9,12 @@ New pragmas:
 - document destructors
 
 - ``borrow`` needs to take type classes into account
-- make use of ``tyIter`` to fix the implicit items/pairs issue
 - ``=`` should be overloadable; requires specialization for ``=``
 - optimize genericAssign in the code generator
 - fix remaining closure bugs:
   - make toplevel but in a scope vars local; make procs there inner procs
   - fix evals.nim with closures
   - implement "closure tuple consists of a single 'ref'" optimization
-  - make 'raiseHook' take a closure and provide push and pop for this
-    --> Lisp-style exception system
 
 - document 'do' notation
 - rethink the syntax: distinction between expr and stmt is unfortunate; 
@@ -43,6 +40,7 @@ version 0.9.XX
   - document it
   - fix exception handling
 
+- make use of ``tyIter`` to fix the implicit items/pairs issue
 - make templates hygienic by default: try to gensym() everything in the 'block'
   of a template; find a better solution for gensym instead of `*ident`
 - introduce 'callsite' magic and make macros and templates the same
@@ -94,6 +92,8 @@ Library
 Low priority
 ------------
 
+- make 'raiseHook' take a closure and provide push and pop for this
+  --> Lisp-style condition system
 - change how comments are part of the AST
 - fix & document ``byCopy`` pragma
 - ``with proc `+`(x, y: T): T`` for generic code