fix empty file

d2lib/d2.go

@@ -35,15 +35,17 @@ func Compile(ctx context.Context, input string, opts *CompileOptions) (*d2target
 		return nil, nil, err
 	}
 
-	err = g.SetDimensions(opts.MeasuredTexts, opts.Ruler)
-	if err != nil {
-		return nil, nil, err
-	}
+	if len(g.Objects) > 0 {
+		err = g.SetDimensions(opts.MeasuredTexts, opts.Ruler)
+		if err != nil {
+			return nil, nil, err
+		}
 
-	if layout, err := getLayout(opts); err != nil {
-		return nil, nil, err
-	} else if err := d2sequence.Layout(ctx, g, layout); err != nil {
-		return nil, nil, err
+		if layout, err := getLayout(opts); err != nil {
+			return nil, nil, err
+		} else if err := d2sequence.Layout(ctx, g, layout); err != nil {
+			return nil, nil, err
+		}
 	}
 
 	diagram, err := d2exporter.Export(ctx, g, opts.ThemeID)

e2etests/e2e_test.go

@@ -38,6 +38,10 @@ func TestE2E(t *testing.T) {
 
 func testSanity(t *testing.T) {
 	tcs := []testCase{
+		{
+			name:   "empty",
+			script: ``,
+		},
 		{
 			name: "basic",
 			script: `a -> b

e2etests/testdata/sanity/empty/dagre/board.exp.json

@@ -0,0 +1,5 @@
+{
+  "name": "",
+  "shapes": [],
+  "connections": []
+}

e2etests/testdata/sanity/empty/dagre/sketch.exp.svg

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg
+style="background: white;"
+xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
+width="202" height="202" viewBox="9223372036854775707 9223372036854775707 202 202"><style type="text/css">
+<![CDATA[
+.shape {
+  shape-rendering: geometricPrecision;
+  stroke-linejoin: round;
+}
+.connection {
+  stroke-linecap: round;
+  stroke-linejoin: round;
+}
+
+]]>
+</style><style type="text/css"><![CDATA[]]></style></svg>

e2etests/testdata/sanity/empty/elk/board.exp.json

@@ -0,0 +1,5 @@
+{
+  "name": "",
+  "shapes": [],
+  "connections": []
+}

e2etests/testdata/sanity/empty/elk/sketch.exp.svg

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg
+style="background: white;"
+xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
+width="202" height="202" viewBox="9223372036854775707 9223372036854775707 202 202"><style type="text/css">
+<![CDATA[
+.shape {
+  shape-rendering: geometricPrecision;
+  stroke-linejoin: round;
+}
+.connection {
+  stroke-linecap: round;
+  stroke-linejoin: round;
+}
+
+]]>
+</style><style type="text/css"><![CDATA[]]></style></svg>