Fixed variable lifetime in loops

src/build/ast/Count.go

@@ -9,6 +9,10 @@ func Count(body AST, kind token.Kind, name string) int {
 	for _, node := range body {
 		switch node := node.(type) {
 		case *Assign:
+			if node.Name.Kind == kind && node.Name.Text() == name {
+				count++
+			}
+
 			count += node.Value.Count(kind, name)
 
 		case *Call:
@@ -18,7 +22,9 @@ func Count(body AST, kind token.Kind, name string) int {
 			count += node.Value.Count(kind, name)
 
 		case *Return:
-			count += node.Value.Count(kind, name)
+			if node.Value != nil {
+				count += node.Value.Count(kind, name)
+			}
 
 		case *If:
 			count += node.Condition.Count(kind, name)

src/build/ast/Parse.go

@@ -30,6 +30,10 @@ func toASTNode(tokens token.List) (Node, error) {
 		word := tokens[0].Text()
 
 		if word == keyword.Return {
+			if len(tokens) == 1 {
+				return &Return{}, nil
+			}
+
 			value := expression.Parse(tokens[1:])
 			return &Return{Value: value}, nil
 		}