[ENHANCEMENT] Throw exception when block type is not set

Throw exception when block type is not set …

Rather than Fatal Error,

Fixes #174 

__Tasks:__

- [x] test coverage
- [x] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes 
| Fixed tickets | #174 
| BC Breaks     | NO 
| Doc           | N.A