Parquet disable full range scan

[jewei1997]

Describe your changes and provide context

If the pebbledb tx index for the new parquet-based receiptdb is disabled, we will currently fallback to range scans over all the parquet files. This is a problem because it is a very expensive operation. This PR disallows the full range scan if the tx index is disabled.

Testing performed to validate your change

unit tests.

[github-actions]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 21, 2026, 8:21 PM

[codecov]

Codecov Report

❌ Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.51%. Comparing base (0ad5733) to head (2d008bd).

Files with missing lines	Patch %	Lines
sei-db/ledger_db/receipt/parquet_store.go	63.63%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3294   +/-   ##
=======================================
  Coverage   58.51%   58.51%           
=======================================
  Files        2072     2072           
  Lines      207938   207942    +4     
=======================================
+ Hits       121676   121687   +11     
+ Misses      77477    77472    -5     
+ Partials     8785     8783    -2     

Flag	Coverage Δ
sei-chain-pr	71.50% <63.63%> (?)
sei-db	69.36% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sei-db/ledger_db/receipt/receipt_store.go	64.89% <ø> (ø)
sei-db/ledger_db/receipt/parquet_store.go	67.89% <63.63%> (+1.93%)	⬆️

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[cody-littley]

Will the end user get a "not found" error, or will they get this message? We should just be telling the user the data is not found, the fact that we aren't doing a scan is probably not helpful to them.

[jewei1997]

Fixed

What the user saw before the UX fix (parquet backend + tx-index-backend = "", query for unknown hash):

  {"jsonrpc":"2.0","id":1,"error":{"code":-32000,
   "message":"receipt tx hash index is disabled; parquet fallback scan is not allowed"}}

Non-standard, leaks internal details, and breaks clients that expect the Ethereum null convention.

What the user sees after the fix:

  {"jsonrpc":"2.0","id":1,"result":null}

Standard Ethereum "unknown tx" behavior.