nvs_flash_init_partition() function

- ESP_OK if storage was successfully initialized. - ESP_ERR_NVS_NO_FREE_PAGES if the NVS storage contains no empty pages (which may happen if NVS partition was truncated) - ESP_ERR_NOT_FOUND if specified partition is not found in the partition table - ESP_ERR_NO_MEM in case memory could not be allocated for the internal structures - one of the error codes from the underlying flash storage driver