fix(sdk): cloud.ApiRequest.body is an empty string for GET requests (…

…#6572)

Fixes #6565

## Checklist

- [ ] Title matches [Winglang's style guide](https://www.winglang.io/contributing/start-here/pull_requests#how-are-pull-request-titles-formatted)
- [ ] Description explains motivation and solution
- [ ] Tests added (always)
- [ ] Docs updated (only required for features)
- [ ] Added `pr/e2e-full` label if this feature requires end-to-end testing

*By submitting this pull request, I confirm that my contribution is made under the terms of the [Wing Cloud Contribution License](https://github.com/winglang/wing/blob/main/CONTRIBUTION_LICENSE.md)*.

examples/tests/sdk_tests/api/get.test.w

@@ -10,7 +10,7 @@ let body = "ok!";
 api.get("/path", inflight (req: cloud.ApiRequest): cloud.ApiResponse => {
   assert(req.method == cloud.HttpMethod.GET);
   assert(req.path == "/path");
-  assert(req.body?.length == 0);
+  assert(req.body == nil);
   assert(req.headers?.get("content-type") == "application/json");
 
   return cloud.ApiResponse {

examples/tests/sdk_tests/api/options.test.w

@@ -9,7 +9,7 @@ let path = "/path";
 api.options(path, inflight (req: cloud.ApiRequest): cloud.ApiResponse => {
   assert(req.method == cloud.HttpMethod.OPTIONS);
   assert(req.path == path);
-  assert(req.body?.length == 0);
+  assert(req.body == nil);
 
   return cloud.ApiResponse {
     status: 204
@@ -19,7 +19,7 @@ api.options(path, inflight (req: cloud.ApiRequest): cloud.ApiResponse => {
 api.head(path, inflight (req: cloud.ApiRequest): cloud.ApiResponse => {
   assert(req.method == cloud.HttpMethod.HEAD);
   assert(req.path == path);
-  assert(req.body?.length == 0);
+  assert(req.body == nil);
 
   return cloud.ApiResponse {
     status: 204

libs/wingsdk/src/target-sim/api.inflight.ts

@@ -314,7 +314,7 @@ export class Api
 function transformRequest(req: express.Request): ApiRequest {
   return {
     headers: sanitizeParamLikeObject(req.headers),
-    body: Object.keys(req.body).length > 0 ? req.body : "",
+    body: Object.keys(req.body).length > 0 ? req.body : undefined,
     method: parseHttpMethod(req.method),
     path: req.path,
     query: sanitizeParamLikeObject(req.query as any),