module check update

The section of the run script that verifies the versions of modules that are loaded currently does the following when a version is not specified:
```
mod_vers, loaded_vers: , 8.5.0
```

I'd like to suggest that instead it add the `default` keyword in place of the empty string in such cases, like so:
```
mod_vers, loaded_vers: default, 8.5.0
```