fix(rest): errors returned from makeRequest() doesn't provide more info rest is proxied (#4012)

packages/rest/src/manager.ts

@@ -533,6 +533,10 @@ export function createRestManager(options: CreateRestManagerOptions): RestManage
     },
 
     async makeRequest(method, route, options) {
+      // This error needs to be created here because of how stack traces get calculated
+      const error = new Error()
+      error.message = 'Failed to send request to discord.'
+
       if (rest.isProxied) {
         if (rest.authorization) {
           options ??= {}
@@ -543,19 +547,28 @@ export function createRestManager(options: CreateRestManagerOptions): RestManage
         const result = await fetch(`${rest.baseUrl}/v${rest.version}${route}`, rest.createRequestBody(method, options))
 
         if (!result.ok) {
+          const errText = await result.text().catch(() => null)
+
+          if (errText) {
+            error.cause = {
+              ok: false,
+              status: result.status,
+              body: errText,
+            }
+
+            throw error
+          }
+
           const err = (await result.json().catch(() => {})) as Record<string, any>
           // Legacy Handling to not break old code or when body is missing
           if (!err?.body) throw new Error(`Error: ${err.message ?? result.statusText}`)
+
           throw new Error(JSON.stringify(err))
         }
 
         return result.status !== 204 ? await result.json() : undefined
       }
 
-      // This error needs to be created here because of how stack traces get calculated
-      const error = new Error()
-      error.message = 'Failed to send request to discord.'
-
       return await new Promise(async (resolve, reject) => {
         const payload: SendRequestOptions = {
           route,