fix: fix panic on blocks with no labels during validation of label na…

…me (#1791)

* fix: fix panic on blocks with no labels during validation of label name

* chore: add changie entry

.changes/unreleased/BUG FIXES-20240808-105000.yaml

@@ -0,0 +1,6 @@
+kind: BUG FIXES
+body: fix panic on blocks with no labels during validation of label name
+time: 2024-08-08T10:50:00.988265+02:00
+custom:
+    Issue: "1791"
+    Repository: terraform-ls

internal/features/stacks/decoder/validations/valid_name.go

@@ -59,7 +59,7 @@ func (sb StackBlockValidName) Visit(ctx context.Context, node hclsyntax.Node, no
 }
 
 func hasValidNameLabel(block *hclsyntax.Block, diags hcl.Diagnostics) hcl.Diagnostics {
-	if !hclsyntax.ValidIdentifier(block.Labels[0]) {
+	if len(block.Labels) > 0 && !hclsyntax.ValidIdentifier(block.Labels[0]) {
 		diags = append(diags, &hcl.Diagnostic{
 			Severity: hcl.DiagError,
 			Summary:  fmt.Sprintf("Invalid %q name %q", block.Type, block.Labels[0]),

internal/features/stacks/decoder/validations/valid_name_test.go

@@ -0,0 +1,20 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validations
+
+import (
+	"testing"
+
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+)
+
+func TestHasValidNameLabel_no_label(t *testing.T) {
+	var diags hcl.Diagnostics
+	block := hclsyntax.Block{
+		Labels: []string{}, // should not panic
+	}
+
+	hasValidNameLabel(&block, diags)
+}