Handle empty Lambda environment. (#10306)

The Lambda environment will be nil if the function has never had an
environment applied. Fixes #10302

builtin/providers/aws/resource_aws_lambda_function.go

@@ -333,7 +333,7 @@ func resourceAwsLambdaFunctionRead(d *schema.ResourceData, meta interface{}) err
 
 	d.Set("source_code_hash", function.CodeSha256)
 
-	if err := d.Set("environment", flattenLambdaEnvironment(function.Environment.Variables)); err != nil {
+	if err := d.Set("environment", flattenLambdaEnvironment(function.Environment)); err != nil {
 		log.Printf("[ERR] Error setting environment for Lambda Function (%s): %s", d.Id(), err)
 	}
 

builtin/providers/aws/resource_aws_lambda_function_test.go

@@ -49,6 +49,15 @@ func TestAccAWSLambdaFunction_envVariables(t *testing.T) {
 		Providers:    testAccProviders,
 		CheckDestroy: testAccCheckLambdaFunctionDestroy,
 		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSLambdaConfigBasic(rName),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsLambdaFunctionExists("aws_lambda_function.lambda_function_test", rName, &conf),
+					testAccCheckAwsLambdaFunctionName(&conf, rName),
+					testAccCheckAwsLambdaFunctionArnHasSuffix(&conf, ":"+rName),
+					resource.TestCheckResourceAttr("aws_lambda_function.lambda_function_test", "environment.#", "0"),
+				),
+			},
 			{
 				Config: testAccAWSLambdaConfigEnvVariables(rName),
 				Check: resource.ComposeTestCheckFunc(

builtin/providers/aws/structure.go

@@ -950,10 +950,15 @@ func flattenDSVpcSettings(
 	return []map[string]interface{}{settings}
 }
 
-func flattenLambdaEnvironment(variables map[string]*string) []interface{} {
+func flattenLambdaEnvironment(lambdaEnv *lambda.EnvironmentResponse) []interface{} {
 	envs := make(map[string]interface{})
 	en := make(map[string]string)
-	for k, v := range variables {
+
+	if lambdaEnv == nil {
+		return nil
+	}
+
+	for k, v := range lambdaEnv.Variables {
 		en[k] = *v
 	}
 	if len(en) > 0 {