Return tree on parse errors

Author: antonmedv

ast/visitor.go

@@ -7,6 +7,9 @@ type Visitor interface {
 }
 
 func Walk(node *Node, v Visitor) {
+	if *node == nil {
+		return
+	}
 	switch n := (*node).(type) {
 	case *NilNode:
 	case *IdentifierNode:

checker/checker.go

@@ -18,7 +18,7 @@ import (
 func ParseCheck(input string, config *conf.Config) (*parser.Tree, error) {
 	tree, err := parser.ParseWithConfig(input, config)
 	if err != nil {
-		return nil, err
+		return tree, err
 	}
 
 	if len(config.Visitors) > 0 {

parser/parser.go

@@ -84,14 +84,16 @@ func ParseWithConfig(input string, config *conf.Config) (*Tree, error) {
 		p.error("unexpected token %v", p.current)
 	}
 
+	tree := &Tree{
+		Node:   node,
+		Source: source,
+	}
+
 	if p.err != nil {
-		return nil, p.err.Bind(source)
+		return tree, p.err.Bind(source)
 	}
 
-	return &Tree{
-		Node:   node,
-		Source: source,
-	}, nil
+	return tree, nil
 }
 
 func (p *parser) error(format string, args ...any) {