fix(tui): show config error details on startup (#27803)

packages/opencode/src/server/routes/instance/httpapi/middleware/error.ts

@@ -1,5 +1,6 @@
 import { NamedError } from "@opencode-ai/core/util/error"
 import * as Log from "@opencode-ai/core/util/log"
+import { ConfigError } from "@/config/error"
 import { Cause, Effect } from "effect"
 import { HttpRouter, HttpServerError, HttpServerRespondable, HttpServerResponse } from "effect/unstable/http"
 
@@ -18,6 +19,13 @@ export const errorLayer = HttpRouter.middleware<{ handles: unknown }>()((effect)
       if (!defect) return Effect.failCause(cause)
 
       const error = defect.defect
+      if (
+        error instanceof NamedError &&
+        (ConfigError.InvalidError.isInstance(error) || ConfigError.JsonError.isInstance(error))
+      ) {
+        return Effect.succeed(HttpServerResponse.jsonUnsafe(error.toObject(), { status: 400 }))
+      }
+
       log.error("failed", { error, cause: Cause.pretty(cause) })
 
       return Effect.succeed(