Enable pylint check: maybe-no-member (E1103)

### Changelog
* Enable `pylint` to flag code using possibly non-existent members.
* Fix a single error that was causing cascades of `E1103` to be spit out.

### Note
This may ocassionally flag correct code. In such a case, it is advisable to write the code in a way that avoids the  error; that way may be cleaner as well. If such a remedy is impossible, the warning can be silenced explicitly.