fix(nestjs): do not make SentryTraced() decorated functions async (#12879)

Author: GitSquared

dev-packages/e2e-tests/test-applications/nestjs/src/app.service.ts

@@ -99,12 +99,14 @@ export class AppService1 {
   }
 
   @SentryTraced('return a string')
-  getString(): string {
-    return 'test';
+  getString(): { result: string } {
+    return { result: 'test' };
   }
 
   async testSpanDecoratorSync() {
-    return this.getString();
+    const returned = this.getString();
+    // Will fail if getString() is async, because returned will be a Promise<>
+    return returned.result;
   }
 
   /*

packages/nestjs/src/span-decorator.ts

@@ -6,7 +6,7 @@ import { startSpan } from '@sentry/node';
 export function SentryTraced(op: string = 'function') {
   return function (target: unknown, propertyKey: string, descriptor: PropertyDescriptor) {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    const originalMethod = descriptor.value as (...args: any[]) => Promise<any>;
+    const originalMethod = descriptor.value as (...args: any[]) => Promise<any> | any; // function can be sync or async
 
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     descriptor.value = function (...args: any[]) {
@@ -15,7 +15,7 @@ export function SentryTraced(op: string = 'function') {
           op: op,
           name: propertyKey,
         },
-        async () => {
+        () => {
           return originalMethod.apply(this, args);
         },
       );