chore: rm nonexhaustive for error

[mattsse]

having non-exhaustive on an error forces this clippy error:

126 | pub enum EVMError<DBError> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: the matched value is of type `EVMError<T>`
    = note: `EVMError<T>` is marked as non-exhaustive, so a wildcard `_` is necessary to match exhaustively
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
    |
192 ~             EVMError::Database(err) => err.into(),
193 ~             _ => todo!(),
    |

this forces a wildcard handling which can introduce bugs if a new evmerror variant is added

[rakita]

This error marks the transaction as Invalid, so I would not assume that it will break things if the subvariant is different.

Would move those two errors behind EnvError: #685 so #[non_exhaustive] is less impactful and would be okay to remove it.