structaccess.Get: handle nil earlier, improve error message (#3660)

Author: denik

acceptance/bundle/resource_deps/missing_ingestion_definition/out.plan.direct-exp.txt

@@ -1,4 +1,4 @@
-Error: cannot resolve "${resources.pipelines.foo.ingestion_definition.connection_name}": field not set: ingestion_definition.connection_name: cannot access key "connection_name" on invalid
+Error: cannot resolve "${resources.pipelines.foo.ingestion_definition.connection_name}": field not set: ingestion_definition: cannot access nil value
 
 Error: cannot plan resources.pipelines.bar: dependency failed: resources.pipelines.foo
 

libs/structs/structaccess/get.go

@@ -36,6 +36,10 @@ func Get(v any, path *structpath.PathNode) (any, error) {
 
 	cur := reflect.ValueOf(v)
 	for _, node := range pathSegments {
+		if node.DotStar() || node.BracketStar() {
+			return nil, fmt.Errorf("wildcards not supported: %s", path.String())
+		}
+
 		var ok bool
 		cur, ok = deref(cur)
 		if !ok {
@@ -55,10 +59,6 @@ func Get(v any, path *structpath.PathNode) (any, error) {
 			continue
 		}
 
-		if node.DotStar() || node.BracketStar() {
-			return nil, fmt.Errorf("wildcards not supported: %s", path.String())
-		}
-
 		key, ok := node.StringKey()
 		if !ok {
 			return nil, errors.New("unsupported path node type")
@@ -288,6 +288,8 @@ func isEmptyForOmitEmpty(v reflect.Value) bool {
 func deref(v reflect.Value) (reflect.Value, bool) {
 	for {
 		switch v.Kind() {
+		case reflect.Invalid:
+			return v, false
 		case reflect.Pointer:
 			if v.IsNil() {
 				return reflect.Value{}, false

libs/structs/structaccess/get_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/databricks/databricks-sdk-go/service/jobs"
+	"github.com/databricks/databricks-sdk-go/service/pipelines"
 	"github.com/stretchr/testify/require"
 )
 
@@ -690,3 +691,12 @@ func TestGetJobSettings(t *testing.T) {
 	testGet(t, &jobSettings, "tasks[0].run_job_task", &jobs.RunJobTask{})
 	testGet(t, &jobSettings, "tasks[0].run_job_task.job_id", int64(0))
 }
+
+func TestPipeline(t *testing.T) {
+	p := pipelines.CreatePipeline{}
+
+	v, err := GetByString(&p, "ingestion_definition.connectin_name")
+	require.Error(t, err)
+	require.Equal(t, "ingestion_definition: cannot access nil value", err.Error())
+	require.Nil(t, v)
+}