refactor(custom-widgets): extract domain package

packages/api/src/router/custom-widget/domain-error.ts

@@ -0,0 +1,16 @@
+import { TRPCError } from "@trpc/server";
+
+import { FlattenError } from "@homarr/common";
+import { CustomWidgetDomainError } from "@homarr/custom-widgets/server";
+
+class RequestLimitTransportError extends FlattenError {}
+
+export function toTrpcError(error: unknown): never {
+  if (error instanceof CustomWidgetDomainError) {
+    const cause = error.retryAfterMs
+      ? new RequestLimitTransportError(error.message, { retryAfterMs: error.retryAfterMs })
+      : error;
+    throw new TRPCError({ code: error.code, message: error.message, cause });
+  }
+  throw error;
+}