diff --git a/ds/dataset.go b/ds/dataset.go
index ec8c7e9..b14ac51 100644
--- a/ds/dataset.go
+++ b/ds/dataset.go
@@ -139,16 +139,24 @@ func (d *Dataset) SetStructure(thread *starlark.Thread, _ *starlark.Builtin, arg
 		return nil, err
 	}
 
-	if err := d.checkField("structure", "schema"); err != nil {
+	if err := d.checkField("structure"); err != nil {
 		return starlark.None, err
 	}
 
 	d.ds.Structure = &dataset.Structure{}
-	if err := json.Unmarshal([]byte(valx.String()), d.ds.Structure); err != nil {
+
+	val, err := util.Unmarshal(valx)
+	if err != nil {
 		return starlark.None, err
 	}
 
-	return starlark.None, nil
+	data, err := json.Marshal(val)
+	if err != nil {
+		return starlark.None, err
+	}
+
+	err = json.Unmarshal(data, d.ds.Structure)
+	return starlark.None, err
 }
 
 // GetBody returns the body of the dataset we're transforming
diff --git a/qri/qri.go b/qri/qri.go
index 970871b..0389811 100644
--- a/qri/qri.go
+++ b/qri/qri.go
@@ -141,7 +141,7 @@ func (m *Module) loadDsHead(refstr string) (*dataset.Dataset, error) {
 	if err := repo.CanonicalizeDatasetRef(m.node.Repo, &ref); err != nil {
 		return nil, err
 	}
-	m.node.LocalStreams.Out.Write([]byte(fmt.Sprintf("loading dataset: %s", ref.String())))
+	m.node.LocalStreams.PrintErr(fmt.Sprintf("load: %s\n", ref.String()))
 
 	ds, err := dsfs.LoadDataset(m.node.Repo.Store(), ref.Path)
 	if err != nil {
diff --git a/startf.go b/startf.go
index 1901d0d..345736b 100644
--- a/startf.go
+++ b/startf.go
@@ -2,4 +2,4 @@ package startf
 
 // Version is the current version of this startf, this version number will be written
 // with each transformation exectution
-const Version = "0.3.0"
+const Version = "0.3.1"
diff --git a/transform.go b/transform.go
index f71a4bb..0ae3db0 100644
--- a/transform.go
+++ b/transform.go
@@ -46,7 +46,7 @@ func AddMutateFieldCheck(check func(path ...string) error) func(o *ExecOpts) {
 	}
 }
 
-// SetOutWriter provides a writer to record the "stdout" of the transform script to
+// SetOutWriter provides a writer to record the "stderr" diagnostic output of the transform script
 func SetOutWriter(w io.Writer) func(o *ExecOpts) {
 	return func(o *ExecOpts) {
 		if w != nil {
@@ -71,7 +71,7 @@ type transform struct {
 	checkFunc func(path ...string) error
 	globals   starlark.StringDict
 	bodyFile  qfs.File
-	stdout    io.Writer
+	stderr    io.Writer
 
 	download starlark.Iterable
 }
@@ -121,12 +121,12 @@ func ExecScript(ds *dataset.Dataset, opts ...func(o *ExecOpts)) error {
 		ds:        ds,
 		skyqri:    skyqri.NewModule(o.Node, ds),
 		checkFunc: o.MutateFieldCheck,
-		stdout:    o.OutWriter,
+		stderr:    o.OutWriter,
 	}
 
 	if o.Node != nil {
 		// if node localstreams exists, write to both localstreams and output buffer
-		t.stdout = io.MultiWriter(o.OutWriter, o.Node.LocalStreams.Out)
+		t.stderr = io.MultiWriter(o.OutWriter, o.Node.LocalStreams.ErrOut)
 	}
 
 	ctx := skyctx.NewContext(ds.Transform.Config, o.Secrets)
@@ -135,7 +135,7 @@ func ExecScript(ds *dataset.Dataset, opts ...func(o *ExecOpts)) error {
 		Load: t.Loader,
 		Print: func(thread *starlark.Thread, msg string) {
 			// note we're ignoring a returned error here
-			_, _ = t.stdout.Write([]byte(msg))
+			_, _ = t.stderr.Write([]byte(msg))
 		},
 	}
 
@@ -167,6 +167,9 @@ func ExecScript(ds *dataset.Dataset, opts ...func(o *ExecOpts)) error {
 	}
 
 	err = callTransformFunc(t, thread, ctx)
+	if evalErr, ok := err.(*starlark.EvalError); ok {
+		return fmt.Errorf(evalErr.Backtrace())
+	}
 
 	// restore consumed script file
 	ds.Transform.SetScriptFile(qfs.NewMemfileBytes("transform.star", buf.Bytes()))
@@ -271,7 +274,7 @@ func (t *transform) setSpinnerMsg(msg string) {
 
 // print writes output only if a node is specified
 func (t *transform) print(msg string) {
-	t.stdout.Write([]byte(msg))
+	t.stderr.Write([]byte(msg))
 }
 
 func (t *transform) Loader(thread *starlark.Thread, module string) (dict starlark.StringDict, err error) {
diff --git a/transform_test.go b/transform_test.go
index 327dbfb..a9a0d6a 100644
--- a/transform_test.go
+++ b/transform_test.go
@@ -28,8 +28,8 @@ func TestExecScript(t *testing.T) {
 	}
 	ds.Transform.SetScriptFile(scriptFile(t, "testdata/tf.star"))
 
-	stdout := &bytes.Buffer{}
-	err := ExecScript(ds, SetOutWriter(stdout))
+	stderr := &bytes.Buffer{}
+	err := ExecScript(ds, SetOutWriter(stderr))
 	if err != nil {
 		t.Error(err.Error())
 		return
@@ -38,14 +38,14 @@ func TestExecScript(t *testing.T) {
 		t.Error("expected transform")
 	}
 
-	output, err := ioutil.ReadAll(stdout)
+	output, err := ioutil.ReadAll(stderr)
 	if err != nil {
 		t.Fatal(err)
 	}
 	expect := `🤖  running transform...
 hello world!`
 	if string(output) != expect {
-		t.Errorf("stdout mismatch. expected: '%s', got: '%s'", expect, string(output))
+		t.Errorf("stderr mismatch. expected: '%s', got: '%s'", expect, string(output))
 	}
 
 	entryReader, err := dsio.NewEntryReader(ds.Structure, ds.BodyFile())