http_header.c: Add error print in http_header_generate_string if buffer size is less than required size

Closes: https://github.com/espressif/esp-idf/issues/5028

components/esp_http_client/lib/http_header.c

@@ -191,6 +191,7 @@ int http_header_generate_string(http_header_handle_t header, int index, char *bu
         if (siz + 1 > *buffer_len - 2) {
             // if this item would not fit to the buffer, return the index of the last fitting one
             ret_idx = idx - 1;
+            ESP_LOGE(TAG, "Buffer length is small to fit all the headers");
             break;
         }
     }