Canvas: Fix worker registration request schema

Make commit information optional and nullable

Change-Id: I181a7ac53f6b1618c11443b168af27e356922ace
diff --git a/apps/canvas/back/src/index.ts b/apps/canvas/back/src/index.ts
index f14cfd1..cd18249 100644
--- a/apps/canvas/back/src/index.ts
+++ b/apps/canvas/back/src/index.ts
@@ -796,6 +796,7 @@
 		const projectId = Number(req.params["projectId"]);
 		const result = WorkerSchema.safeParse(req.body);
 		if (!result.success) {
+			console.log(JSON.stringify(result.error));
 			resp.status(400);
 			resp.write(
 				JSON.stringify({