Harden gameplay timing and map loading

lib/service-error.ts

@@ -0,0 +1,16 @@
+export class ServiceError extends Error {
+  constructor(
+    message: string,
+    public readonly status = 503,
+  ) {
+    super(message);
+  }
+}
+
+export function checkServiceError(error: { message: string; code?: string } | null) {
+  if (!error) return;
+  if (error.code === "P0001") throw new Error(error.message);
+  if (error.code === "PGRST116") throw new ServiceError("Record not found", 404);
+  console.error("Supabase request failed:", error.code, error.message);
+  throw new ServiceError("MineGeo could not reach its data service. Please try again.");
+}