fixes yet another regression caused by the .procvar removal

compiler/sempass2.nim

@@ -783,6 +783,10 @@ proc track(tracked: PEffects, n: PNode) =
           notNilCheck(tracked, last, child.sons[i].typ)
       # since 'var (a, b): T = ()' is not even allowed, there is always type
       # inference for (a, b) and thus no nil checking is necessary.
+  of nkConstSection:
+    for child in n:
+      let last = lastSon(child)
+      track(tracked, last)
   of nkCaseStmt: trackCase(tracked, n)
   of nkWhen, nkIfStmt, nkIfExpr: trackIf(tracked, n)
   of nkBlockStmt, nkBlockExpr: trackBlock(tracked, n.sons[1])