Merge pull request #31587 from hashicorp/b-null-tag-values

Tags: fix for null tags in config

.changelog/31587.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+provider/tags: Fix crash when tags are `null`
+```

internal/service/ec2/vpc_test.go

@@ -157,6 +157,28 @@ func TestAccVPC_tags_computed(t *testing.T) {
 	})
 }
 
+func TestAccVPC_tags_null(t *testing.T) {
+	ctx := acctest.Context(t)
+	var vpc ec2.Vpc
+	resourceName := "aws_vpc.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(ctx, t) },
+		ErrorCheck:               acctest.ErrorCheck(t, ec2.EndpointsID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckVPCDestroy(ctx),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccVPCConfig_tags_null,
+				Check: resource.ComposeTestCheckFunc(
+					acctest.CheckVPCExists(ctx, resourceName, &vpc),
+					resource.TestCheckResourceAttr(resourceName, "tags.%", "0"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccVPC_DefaultTags_zeroValue(t *testing.T) {
 	ctx := acctest.Context(t)
 	var vpc ec2.Vpc
@@ -1139,6 +1161,16 @@ resource "aws_vpc" "test" {
 }
 `
 
+const testAccVPCConfig_tags_null = `
+resource "aws_vpc" "test" {
+  cidr_block = "10.1.0.0/16"
+
+  tags = {
+    Name = null
+  }
+}
+`
+
 func testAccVPCConfig_ignoreChangesDynamicTagsMergedLocals(localTagKey1, localTagValue1 string) string {
 	return fmt.Sprintf(`
 locals {

internal/tags/key_value_tags.go

@@ -780,7 +780,10 @@ func (tags KeyValueTags) ResolveDuplicates(ctx context.Context, defaultConfig *D
 		if !c.IsNull() && c.IsKnown() {
 			for k, v := range c.AsValueMap() {
 				if _, ok := configTags[k]; !ok {
-					configTags[k] = v.AsString()
+					// config tags can be null values. Ignore.
+					if !v.IsNull() {
+						configTags[k] = v.AsString()
+					}
 				}
 			}
 		}