Fixed shellcheck warnings SC2178 and SC2128.
Fixed shellcheck warnings SC2178 and SC2128.

SC2178: Variable was used as an array but is now assigned a string.
SC2128: Expanding an array without an index only gives the first element.

It's apparently a known bug that shellcheck can't both declare a
variable local and assign a value to it without raising this issue.
https://github.com/koalaman/shellcheck/wiki/SC2178

pivpn/pivpn