Bug/leak at payload parse error

### Description
Fixed a possible memory leak in case of parse error.

### Code Details
The output parameter 'reqPP' was set too late, after an error return for a parse error in either XML or JSON  parse. As reqPP was unset, the receiver could not free the allocated memory in the release method.
Now 'reqPP' is set at an earlier stage and deletion of the allocated objects can be performed.

This bug exists in the 'develop' branch also but is not yet visible.
As soon as 'feature/complex_field_values' is merged into 'develop' there is no longer any problem with this.