Nethermind block test behavior differs from geth/reth/besu

[R9295]

Issue Description

Nethermind skips a rejected block if a block header is null, while Geth, Reth and Besu still execute the block and attempt insertion. Block header is typically null for expectException blocks, which tests if a given invalid block is to be rejected. This results in certain block tests passing since nethermind skips invalid blocks.
Additionally, this invokes a scenario where you cannot test whether invalid blocks are to be rejected..

PoC

The PoC JSON of the block test exceeds the character limit of GitHub issues, so it is present in a separate gist here:

https://gist.github.com/R9295/40e5850c459acbffa3e82e2f41beaabd