refactor: standardize error handling with toError() helper

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/routes/tournaments.ts

@@ -1,6 +1,7 @@
 import { Hono } from 'hono'
 import { db, schema } from '../db/index.js'
 import { eq } from 'drizzle-orm'
+import { toError } from '../lib/utils.js'
 import {
   createTournament,
   joinTournament,
@@ -73,7 +74,7 @@ tournamentsRouter.post('/:id/join', async (c) => {
     const entryId = joinTournament(tournamentId, bot.id, body.paymentId)
     return c.json({ entryId, botId: bot.id })
   } catch (err) {
-    const message = err instanceof Error ? err.message : String(err)
+    const message = toError(err).message
     return c.json({ error: message }, 400)
   }
 })
@@ -92,7 +93,7 @@ tournamentsRouter.post('/:id/start', async (c) => {
     const bracket = getTournamentBracket(tournamentId)
     return c.json({ status: 'active', bracket })
   } catch (err) {
-    const message = err instanceof Error ? err.message : String(err)
+    const message = toError(err).message
     return c.json({ error: message }, 400)
   }
 })