fix(ui): keep a Slack upstream fault inside the action's answer

- Await the refusal mapping so a server fault becomes the action's own
  error instead of escaping the catch
- Expect the refusal code the actions now carry in their unit tests

ui/actions/integrations/slack.test.ts

@@ -456,7 +456,7 @@ describe("getSlackChannels", () => {
 
     const result = await getSlackChannels(SLACK_INTEGRATION_ID);
 
-    expect(result).toEqual({ error: RATE_LIMITED_MESSAGE });
+    expect(result).toEqual({ error: RATE_LIMITED_MESSAGE, code: null });
   });
 });
 
@@ -633,6 +633,8 @@ describe("sendSlackTestMessage", () => {
 
     expect(result).toEqual({
       error: SLACK_ERROR_MESSAGES[SLACK_ERROR_CODE.NOT_IN_CHANNEL],
+      // The reason travels on as the class it is, not only as its sentence.
+      code: SLACK_ERROR_CODE.NOT_IN_CHANNEL,
     });
   });
 
@@ -730,7 +732,8 @@ describe.each(COPY_ONLY_ACTIONS)("$name", ({ call }) => {
 
     expect(captureExceptionMock).not.toHaveBeenCalled();
     expect(captureMessageMock).not.toHaveBeenCalled();
-    expect(result).toEqual({ error: refusal.expected });
+    // `code` travels alongside the copy; none of these refusals names one.
+    expect(result).toEqual({ error: refusal.expected, code: null });
   });
 });
 

ui/actions/integrations/slack.ts

@@ -452,7 +452,9 @@ export const setSlackDefaultChannel = async (
     });
 
     if (!response.ok) {
-      return refusalFrom(
+      // Awaited inside the `try`: unawaited, a 5xx's rejection would skip
+      // this `catch`.
+      return await refusalFrom(
         response,
         `Unable to save the destination channel: ${response.statusText}`,
       );
@@ -509,7 +511,9 @@ export const sendSlackTestMessage = async (
     const response = await fetch(url.toString(), { method: "POST", headers });
 
     if (!response.ok) {
-      return refusalFrom(
+      // Awaited inside the `try`: unawaited, a 5xx's rejection would skip
+      // this `catch`.
+      return await refusalFrom(
         response,
         `Unable to send the test message: ${response.statusText}`,
       );
@@ -610,7 +614,9 @@ export const disconnectSlackIntegration = async (
     const response = await fetch(url.toString(), { method: "DELETE", headers });
 
     if (!response.ok) {
-      return refusalFrom(
+      // Awaited inside the `try`: unawaited, a 5xx's rejection would skip
+      // this `catch`.
+      return await refusalFrom(
         response,
         `Unable to disconnect the Slack workspace: ${response.statusText}`,
       );