fix: Distinguish between ErrTxnHashNotFound and ErrInternal

[hudem1]

rpc pkg cleanup according to issue #2437

• for v6: Updated handler code to take into account pending block as well.

• for v7: Reuse v6 handler for v7 as the logic is the same.

• for v8: The logic is the same as v6/v7, but not exactly the returned Transaction type (more particularly, Resource type inside Transaction type). Therefore, we cannot refactor v8's types or logic

[AnkushinDaniil]

We should also be handling the pending block in v6 in the same way. As far as I know, this difference happened because the old code for v6 was copied in #2419 . You can use the same code from v7 and continue refactoring.

[codecov]

Codecov Report

Attention: Patch coverage is 47.05882% with 9 lines in your changes missing coverage. Please review.

Project coverage is 73.69%. Comparing base (0ddfa64) to head (df42ccc).

Files with missing lines	Patch %	Lines
rpc/v6/transaction.go	43.75%	6 Missing and 3 partials ⚠️

❌ Your patch check has failed because the patch coverage (47.05%) is below the target coverage (60.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2486      +/-   ##
==========================================
- Coverage   73.78%   73.69%   -0.09%     
==========================================
  Files         138      138              
  Lines       16925    16919       -6     
==========================================
- Hits        12488    12469      -19     
- Misses       3571     3580       +9     
- Partials      866      870       +4     

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[hudem1]

We should also be handling the pending block in v6 in the same way. As far as I know, this difference happened because the old code for v6 was copied in #2419 . You can use the same code from v7 and continue refactoring.

Ah yes indeed, good catch! I updated v6 code, and I could then reuse v6 handler for v7.