rename to _tempObject and give type void * so it can be used for any object/array

src/ESPAsyncWebServer.h

@@ -160,7 +160,7 @@ class AsyncWebServerRequest {
 
   public:
     File _tempFile;
-    uint8_t *_tempBuffer;
+    void *_tempObject;
     AsyncWebServerRequest *next;
 
     AsyncWebServerRequest(AsyncWebServer*, AsyncClient*);

src/WebRequest.cpp

@@ -63,7 +63,7 @@ AsyncWebServerRequest::AsyncWebServerRequest(AsyncWebServer* s, AsyncClient* c)
   , _itemBuffer(0)
   , _itemBufferIndex(0)
   , _itemIsFile(false)
-  , _tempBuffer(NULL)
+  , _tempObject(NULL)
   , next(NULL)
 {
   c->onError([](void *r, AsyncClient* c, int8_t error){ AsyncWebServerRequest *req = (AsyncWebServerRequest*)r; req->_onError(error); }, this);