Interpreter error message not clear

[samuelmanzanera]

Describe the problem you discovered

If we pass a smart contract code with just the following code:

@version 1

We get an error which is not accurate:

unexpected term - @:atom => \"version\"(1) - L1

This issue seems to related to a pattern matching issue

https://github.com/archethic-foundation/archethic-node/blob/31cc63def92a24b74a5133f3c8f19a7d3e9a7886/lib/archethic/contracts/interpreter.ex#L36C10-L38C44

Describe the solution you'd like

The interpreter should accept @version 1 without having a block or mention the contract cannot be empty with only the version mention.

Epic

#608