This includes a move from github.com/StackExchange/wmi to
github.com/yusufpapurcu/wmi, as the StackExchange repository has been
archived.
Signed-off-by: Ben Reedy <breed808@breed808.com>
If an WMI query were to return an empty result set, trying to access the
first element in the result set would result in a `panic: runtime error:
index out of range` error.
add logic to explicitly check if the result set size is 0 and return an
error rather.
Fixes https://github.com/martinlindhe/wmi_exporter/issues/240
