Handle promise rejection and synchronous errors in monitoring

Added error capturing for both synchronous and asynchronous exceptions in monitored methods. Incorporated `isThenable` checks to handle promises properly, ensuring robust error tracking with Sentry in both cases.

Author: cod1k

packages/core/src/exports.ts

@@ -175,15 +175,16 @@ export function withMonitor<T>(
     }
 
     if (isThenable(maybePromiseResult)) {
-      Promise.resolve(maybePromiseResult).then(
-        () => {
+      return maybePromiseResult.then(
+        r => {
           finishCheckIn('ok');
+          return r;
         },
         e => {
           finishCheckIn('error');
           throw e;
         },
-      );
+      ) as T;
     } else {
       finishCheckIn('ok');
     }

packages/nestjs/src/decorators.ts

@@ -1,5 +1,5 @@
 import type { MonitorConfig } from '@sentry/core';
-import { captureException } from '@sentry/core';
+import { captureException, isThenable } from '@sentry/core';
 import * as Sentry from '@sentry/node';
 import { startSpan } from '@sentry/node';
 import { isExpectedError } from './helpers';
@@ -15,7 +15,20 @@ export const SentryCron = (monitorSlug: string, monitorConfig?: MonitorConfig):
       return Sentry.withMonitor(
         monitorSlug,
         () => {
-          return originalMethod.apply(this, args);
+          let result;
+          try {
+            result = originalMethod.apply(this, args);
+          } catch (e) {
+            captureException(e);
+            throw e;
+          }
+          if (isThenable(result)) {
+            return result.then(undefined, e => {
+              captureException(e);
+              throw e;
+            });
+          }
+          return result;
         },
         monitorConfig,
       );