feat: add onError support to serve (#79)

* feat: add onError support to serve

* fix: use console.error as default onError and use onError in try/catch

---------

Co-authored-by: CahidArda <[email protected]>

Author: teovillanueva

src/error.ts

@@ -56,6 +56,8 @@ export const formatWorkflowError = (error: unknown): FailureFunctionPayload => {
       }
     : {
         error: "Error",
-        message: "An error occured while executing workflow.",
+        message:
+          "An error occured while executing workflow: " +
+          `'${typeof error === "string" ? error : JSON.stringify(error)}'`,
       };
 };

src/serve/index.ts

@@ -62,6 +62,7 @@ export const serveBase = <
     useJSONContent,
     disableTelemetry,
     flowControl,
+    onError,
   } = processOptions<TResponse, TInitialPayload>(options);
   telemetry = disableTelemetry ? undefined : telemetry;
   const debug = WorkflowLogger.getLogger(verbose);
@@ -234,8 +235,21 @@ export const serveBase = <
     try {
       return await handler(request);
     } catch (error) {
-      console.error(error);
-      return new Response(JSON.stringify(formatWorkflowError(error)), {
+      const formattedError = formatWorkflowError(error);
+      try {
+        onError?.(error as Error);
+      } catch (onErrorError) {
+        const formattedOnErrorError = formatWorkflowError(onErrorError);
+        const errorMessage =
+          `Error while running onError callback: '${formattedOnErrorError.message}'.` +
+          `\nOriginal error: '${formattedError.message}'`;
+
+        console.error(errorMessage);
+        return new Response(errorMessage, {
+          status: 500,
+        }) as TResponse;
+      }
+      return new Response(JSON.stringify(formattedError), {
         status: 500,
       }) as TResponse;
     }

src/serve/options.ts

@@ -91,6 +91,7 @@ export const processOptions = <TResponse extends Response = Response, TInitialPa
     retries: DEFAULT_RETRIES,
     useJSONContent: false,
     disableTelemetry: false,
+    onError: console.error,
     ...options,
   };
 };

src/serve/serve.test.ts

@@ -253,6 +253,7 @@ describe("serve", () => {
   });
 
   test("should return 500 on error during step execution", async () => {
+    let onErrorCalled = false;
     const { handler: endpoint } = serve(
       async (context) => {
         await context.run("wrong step", async () => {
@@ -262,6 +263,11 @@ describe("serve", () => {
       {
         qstashClient,
         receiver: undefined,
+        onError(error) {
+          expect(error).toBeInstanceOf(Error);
+          expect(error.message).toBe("some-error");
+          onErrorCalled = true;
+        },
       }
     );
 
@@ -284,6 +290,7 @@ describe("serve", () => {
       receivesRequest: false,
     });
     expect(called).toBeTrue();
+    expect(onErrorCalled).toBeTrue();
   });
 
   test("should call onFinish with auth-fail if authentication fails", async () => {

src/types.ts

@@ -174,6 +174,14 @@ export type WorkflowServeOptions<
    * Url to call if QStash retries are exhausted while executing the workflow
    */
   failureUrl?: string;
+
+  /**
+   * Error handler called when an error occurs in the workflow. This is
+   * different from `failureFunction` in that it is called when an error
+   * occurs in the workflow, while `failureFunction` is called when QStash
+   * retries are exhausted.
+   */
+  onError?: (error: Error) => void;
   /**
    * Failure function called when QStash retries are exhausted while executing
    * the workflow. Will overwrite `failureUrl` parameter with the workflow