Canvas: Fix worker registration request schema

Make commit information optional and nullable

Change-Id: I181a7ac53f6b1618c11443b168af27e356922ace
diff --git a/apps/canvas/config/src/graph.ts b/apps/canvas/config/src/graph.ts
index 94708b4..604bcc4 100644
--- a/apps/canvas/config/src/graph.ts
+++ b/apps/canvas/config/src/graph.ts
@@ -286,20 +286,21 @@
 	workers: z.array(
 		z.object({
 			id: z.string(),
-			commit: z.optional(
-				z.object({
+			commit: z
+				.object({
 					hash: z.string(),
 					message: z.string(),
-				}),
-			),
-			commands: z.optional(
-				z.array(
+				})
+				.nullable()
+				.optional(),
+			commands: z
+				.array(
 					z.object({
 						command: z.string(),
 						state: z.string(),
 					}),
-				),
-			),
+				)
+				.optional(),
 		}),
 	),
 });