Revert "Refactor the code of the post processor to work properly."

This reverts commit e89163c608f27cd34cd871b6bcb814a24b65c762.

Reason: this commit breaks writing reports.
Revert "Do not raise an exception on no input processor."

This reverts commit 77cfa98526f43919619dacf27a0f5c2644313985.

Reason: this commit breaks writing reports.