introduce fallback empty strings when uci for wan6 misses some options

7 jobs for fix-crashes-on-missing-wan6-options in 9 minutes and 25 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Test
passed #470348
blackbox_mock_mqtt

00:02:39

passed #470349
blackbox_openwrt_mqtt

00:09:04

passed #470350
blackbox_openwrt_ubus

00:09:24

passed #470347
blackbox_openwrt_unix_socket

00:09:11

passed #470345
flake8

00:01:20

passed #470351
sample_module

00:02:10

passed #470346
unit_tests

00:02:10