Check merge alias is a map #1425

pkg/yqlib/operator_anchors_aliases.go

@@ -2,6 +2,7 @@ package yqlib
 
 import (
 	"container/list"
+	"fmt"
 
 	yaml "gopkg.in/yaml.v3"
 )
@@ -244,6 +245,9 @@ func applyAlias(node *yaml.Node, alias *yaml.Node, aliasIndex int, newContent Co
 	if alias == nil {
 		return nil
 	}
+	if alias.Kind != yaml.MappingNode {
+		return fmt.Errorf("merge anchor only supports maps, got %v instead", alias.Tag)
+	}
 	for index := 0; index < len(alias.Content); index = index + 2 {
 		keyNode := alias.Content[index]
 		log.Debugf("applying alias key %v", keyNode.Value)

pkg/yqlib/operator_anchors_aliases_test.go

@@ -36,6 +36,13 @@ thingTwo:
 `
 
 var anchorOperatorScenarios = []expressionScenario{
+	{
+		skipDoc:       true,
+		description:   "merge anchor not map",
+		document:      "a: &a\n  - 0\nc:\n  <<: [*a]\n",
+		expectedError: "merge anchor only supports maps, got !!seq instead",
+		expression:    "explode(.)",
+	},
 	{
 		description:    "Merge one map",
 		subdescription: "see https://yaml.org/type/merge.html",