Can't call method "selectall_arrayref" on unblessed reference

When trying to run `mosmix-query.pl`:
```
Can't call method "selectall_arrayref" on unblessed reference at /opt/perl-5.28.1/lib/site_perl/5.28.1/Weather/MOSMIX.pm line 267.
```
In fact, `$f` returned by `$w->forecast` does not return a `$dbh` which is expected by `$w->format_forecast_dbh`