More clear exception message for null/empty strings

[codecov[bot]]

Codecov Report

Merging #394 (535ea8d) into develop (9f3153d) will not change coverage. The diff coverage is 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #394 +/- ## ========================================== Coverage 92.89% 92.89% Complexity 2141 2141 ========================================== Files 125 125 Lines 7483 7483 Branches 1198 1198 ========================================== Hits 6951 6951 Misses 489 489 Partials 43 43 ```