fix(node): Preserve synchronous return behavior for streamText and other methods for AI

packages/node/src/integrations/tracing/vercelai/instrumentation.ts

@@ -71,7 +71,7 @@ function isToolError(obj: unknown): obj is ToolError {
  * Check for tool errors in the result and capture them
  * Tool errors are not rejected in Vercel V5, it is added as metadata to the result content
  */
-function checkResultForToolErrors(result: unknown | Promise<unknown>): void {
+function checkResultForToolErrors(result: unknown): void {
   if (typeof result !== 'object' || result === null || !('content' in result)) {
     return;
   }
@@ -132,6 +132,15 @@ function checkResultForToolErrors(result: unknown | Promise<unknown>): void {
   }
 }
 
+/**
+ * Checks if the given value is a promise like object.
+ * @param value The value to check.
+ * @returns True if the value is a promise like object, false otherwise.
+ */
+function isPromiseLike<T = unknown>(value: unknown): value is PromiseLike<T> {
+  return !!value && typeof value === 'object' && typeof (value as { then?: unknown }).then === 'function';
+}
+
 /**
  * Determines whether to record inputs and outputs for Vercel AI telemetry based on the configuration hierarchy.
  *
@@ -236,13 +245,18 @@ export class SentryVercelAiInstrumentation extends InstrumentationBase {
         };
 
         return handleCallbackErrors(
-          async () => {
+          () => {
             // @ts-expect-error we know that the method exists
-            const result = await originalMethod.apply(this, args);
+            const result = originalMethod.apply(this, args);
 
-            // Tool errors are not rejected in Vercel V5, it is added as metadata to the result content
-            checkResultForToolErrors(result);
+            if (isPromiseLike(result)) {
+              // check for tool errors when the promise resolves, keep the original promise identity
+              result.then(checkResultForToolErrors, () => {});
+              return result;
+            }
 
+            // check for tool errors when the result is synchronous
+            checkResultForToolErrors(result);
             return result;
           },
           error => {