[PM-10259] improve forwarder rpc error handling (#10330)

* only accept `application/json` responses

libs/tools/generator/core/src/engine/rpc/create-forwarding-address.spec.ts

@@ -37,7 +37,7 @@ describe("CreateForwardingAddressRpc", () => {
       expect(result.cache).toEqual("no-store");
       expect(result.method).toEqual("POST");
       expect(result.headers.get("Content-Type")).toEqual("application/json");
-      expect(result.headers.get("X-Requested-With")).toEqual("XMLHttpRequest");
+      expect(result.headers.get("Accept")).toEqual("application/json");
     });
 
     it("provides the request and context to the rpc definition functions", () => {

libs/tools/generator/core/src/engine/rpc/create-forwarding-address.ts

@@ -29,10 +29,8 @@ export class CreateForwardingAddressRpc<
       method: "POST",
       headers: new Headers({
         ...token,
-        // X-Requested-With header required by some endpoints for
-        // detailed error descriptions (see #5565)
-        "X-Requested-With": "XMLHttpRequest",
         "Content-Type": "application/json",
+        Accept: "application/json",
       }),
       body,
     });

libs/tools/generator/core/src/engine/rpc/get-account-id.spec.ts

@@ -32,6 +32,7 @@ describe("GetAccountIdRpc", () => {
       expect(result.cache).toEqual("no-store");
       expect(result.method).toEqual("GET");
       expect(result.headers.get("Content-Type")).toEqual("application/json");
+      expect(result.headers.get("Accept")).toEqual("application/json");
     });
 
     it("provides the request and context to the rpc definition functions", () => {

libs/tools/generator/core/src/engine/rpc/get-account-id.ts

@@ -33,6 +33,7 @@ export class GetAccountIdRpc<
       headers: new Headers({
         ...token,
         "Content-Type": "application/json",
+        Accept: "application/json",
       }),
     });