workflow: ensure we handle trailing null values (#13616)

* handle null inputs

* format

* add changeset

* lint

* init with default

* add changeset

* tweak

* format

* add changeset

* remove empty

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>

Author: hannahblair

.changeset/three-tigers-fold.md

@@ -0,0 +1,6 @@
+---
+"@gradio/workflowcanvas": minor
+"gradio": minor
+---
+
+feat:workflow: ensure we handle trailing null values

js/workflowcanvas/workflow/WorkflowCanvas.svelte

@@ -45,6 +45,7 @@
 		WFEdge,
 		NodeStatus,
 		NodeRole,
+		NodeDataValue,
 		Workflow
 	} from "./workflow-types";
 	import { executeWorkflow } from "./workflow-executor";
@@ -490,6 +491,11 @@
 					template.height
 				);
 				const newId = addNode("reference", template, x, y);
+				const port = node.inputs.find((p) => p.id === portId);
+				if (port?.default_value !== undefined) {
+					const outId = template.outputs[0]?.id ?? "out";
+					updateNodeData(newId, outId, port.default_value as NodeDataValue);
+				}
 				addEdge({
 					from_node_id: newId,
 					from_port_id: "out",
@@ -2032,6 +2038,13 @@
 						inStartY + i * (compH + compGap)
 					);
 					const cId = addNode("reference", comp, cx, cy);
+					if (port.default_value !== undefined) {
+						updateNodeData(
+							cId,
+							comp.outputs[0]?.id ?? "out",
+							port.default_value as NodeDataValue
+						);
+					}
 					addEdge({
 						from_node_id: cId,
 						from_port_id: "out",

js/workflowcanvas/workflow/workflow-store.ts

@@ -94,6 +94,11 @@ export function sanitize_for_save(wf: Workflow): Workflow {
 }
 
 // ─── Actions ────────────────────────────────────────────────────────────────
+const PORT_DEFAULTS: Partial<Record<PortType, NodeDataValue>> = {
+	boolean: false,
+	number: 0,
+	text: ""
+};
 
 function addReference(
 	template: Omit<ReferenceNode, "id" | "role" | "x" | "y" | "data">,
@@ -102,9 +107,11 @@ function addReference(
 ): string {
 	const id = uuid();
 	const data: Record<string, NodeDataValue> = {};
-	for (const port of template.inputs) {
+	for (const port of [...template.inputs, ...template.outputs]) {
 		if (port.default_value !== undefined) {
 			data[port.id] = port.default_value as NodeDataValue;
+		} else if (port.type in PORT_DEFAULTS) {
+			data[port.id] ??= PORT_DEFAULTS[port.type]!;
 		}
 	}
 	const node: ReferenceNode = {