fix(sse): refine error reporting

Author: weareoutman

packages/utils/src/general/createSSEStream.spec.ts

@@ -139,6 +139,53 @@ describe("createSSEStream", () => {
     expect(consoleError).toHaveBeenCalledWith("open error", "Internal Error");
   });
 
+  test("open error with json error", async () => {
+    mockFetchEventSource.mockImplementation(async (_url, options) => {
+      const { onopen, onerror } = options;
+      await Promise.resolve();
+      try {
+        await onopen?.({
+          ok: false,
+          statusText: "Internal Error",
+          text: () =>
+            Promise.resolve(
+              JSON.stringify({
+                error: "Something went wrong",
+              })
+            ),
+        } as Response);
+      } catch (e) {
+        await onerror?.(e);
+      }
+    });
+    await expect(createSSEStream(url)).rejects.toMatchInlineSnapshot(
+      `[Error: Something went wrong]`
+    );
+    expect(consoleError).toHaveBeenCalledTimes(1);
+    expect(consoleError).toHaveBeenCalledWith("open error", "Internal Error");
+  });
+
+  test("open error with non-json error", async () => {
+    mockFetchEventSource.mockImplementation(async (_url, options) => {
+      const { onopen, onerror } = options;
+      await Promise.resolve();
+      try {
+        await onopen?.({
+          ok: false,
+          statusText: "Internal Error",
+          text: () => Promise.resolve("Oops"),
+        } as Response);
+      } catch (e) {
+        await onerror?.(e);
+      }
+    });
+    await expect(createSSEStream(url)).rejects.toMatchInlineSnapshot(
+      `[Error: Oops]`
+    );
+    expect(consoleError).toHaveBeenCalledTimes(1);
+    expect(consoleError).toHaveBeenCalledWith("open error", "Internal Error");
+  });
+
   test("message error", async () => {
     mockFetchEventSource.mockImplementation(async (_url, options) => {
       const { onopen, onmessage } = options;

packages/utils/src/general/createSSEStream.ts

@@ -62,7 +62,24 @@ export async function createSSEStream<T = unknown>(
         } else {
           // eslint-disable-next-line no-console
           console.error("open error", response.statusText);
-          throw new Error(response.statusText);
+          let text: string;
+          try {
+            text = await response.text();
+          } catch {
+            throw new Error(response.statusText);
+          }
+
+          let json: any;
+          try {
+            json = JSON.parse(text);
+          } catch {
+            // Do nothing
+          }
+
+          if (typeof json?.error === "string") {
+            throw new Error(json.error);
+          }
+          throw new Error(text);
         }
       },
       onmessage(msg) {