[FS#1030] ubus call network reload fails with unknown error

[LEDE Bugs]

The following task has a new comment added:

FS#1030 - ubus call network reload fails with unknown error
User who did this - Val Kulkov (val-kulkov)

----------
If a device has no wireless interfaces, the uci config for the wireless will fail and netifd's config_init_all() function will return -1: https://git.lede-project.org/?p=project/netifd.git;a=blob;f=config.c;h=a7112f042a677426ab27baff8b8131e0bb4e3d40;hb=HEAD#l424

The return value of -1 then propagates to netifd_reload(): 
https://git.lede-project.org/?p=project/netifd.git;a=blob;f=main.c;h=c173cef35be5a840d1d9d5d3b67c3eeab3f0c3b0;hb=HEAD#l213

and then to netifd_handle_reload()
https://git.lede-project.org/?p=project/netifd.git;a=blob;f=ubus.c;h=bf7267239ccc7ab16625fc658f1a04cfcc015db7;hb=HEAD#l48

The suggested fix is to check for presence of /etc/config/wireless and return -1 only if the file is present.
----------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1030#comment3544