Fix the decoding of unsigned transactions

[pienkowb]

Currently, the transaction decoding methods (both for EIP-1559 and EIP-2930) try to recover a sender address for unsigned transactions, which results in the following error:

lib/eth/chain.rb:161:in `+': nil can't be coerced into Integer (TypeError)

        v = 2 * chain_id + 35 + recovery_id
                                ^^^^^^^^^^^

This PR fixes this issue by checking if recovery_id is present.

[q9f]

Thanks. You can ignore the failing actions (lack of permissions for external contributors).

Do you mind adding a test for that?

[pienkowb]

Do you mind adding a test for that?

@q9f Done 👍

[codecov-commenter]

Codecov Report

Merging #243 (6efcd1a) into main (6f19a28) will decrease coverage by 0.18%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##             main     #243      +/-   ##
==========================================
- Coverage   99.66%   99.48%   -0.18%     
==========================================
  Files          77       77              
  Lines        4439     4460      +21     
==========================================
+ Hits         4424     4437      +13     
- Misses         15       23       +8     

Files Changed	Coverage Δ
lib/eth/tx/legacy.rb	100.00% <ø> (ø)
lib/eth/tx/eip1559.rb	99.35% <100.00%> (+0.65%)	⬆️
lib/eth/tx/eip2930.rb	99.32% <100.00%> (+0.68%)	⬆️
spec/eth/tx_spec.rb	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

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[pienkowb]

@q9f I've added a test case for an EIP-2930 transaction too, so that the test coverage is not decreased.

[pienkowb]

@q9f Is there anything else we need before this PR can be merged?

[q9f]

Sorry, it's slow season over hear. I'll take care of it now :)