When we read the MUC configuration, a file which exists but is empty
will not error, but will cause all configuration to be empty.
We already perform an {{is_array()}} check on the {{$configuration}}
variable, but the default value for {{$configuration}} is an empty
array. In the case where the file exists, but is empty, no errors occur
when the file is loaded, and the initial {{$configuration}} value is
not overwritten, leading to the file being replaced with an empty copy.
Andrew Nicols
b26a5e5e08