Fix error when supplying multiple resources to manifest_decode()

Author: jrhouston

internal/framework/provider/functions/manifest_decode.go

@@ -56,6 +56,7 @@ func (f ManifestDecodeFunction) Run(ctx context.Context, req function.RunRequest
 		return
 	} else if len(elems) > 1 {
 		resp.Error = function.NewFuncError("YAML manifest contains multiple resources: use decode_manifest_multi to decode manifests containing more than one resource")
+		return
 	}
 
 	dynamResp := types.DynamicValue(elems[0])

internal/framework/provider/functions/manifest_decode_test.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"regexp"
 	"testing"
 
 	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
@@ -44,6 +45,20 @@ func TestManifestDecode(t *testing.T) {
 	})
 }
 
+func TestManifestDecode_ErrorOnMulti(t *testing.T) {
+	t.Parallel()
+
+	resource.UnitTest(t, resource.TestCase{
+		ProtoV5ProviderFactories: testAccProtoV5ProviderFactories,
+		Steps: []resource.TestStep{
+			{
+				Config:      testManifestDecodeConfig("testdata/decode_multi.yaml"),
+				ExpectError: regexp.MustCompile(`YAML\s+manifest\s+contains\s+multiple\s+resources`),
+			},
+		},
+	})
+}
+
 func testManifestDecodeConfig(filename string) string {
 	cwd, _ := os.Getwd()
 	return fmt.Sprintf(`