"Invalid character" error in indexed event

"indexed uint256 event" with value 10 ~ 15 (hex a ~ f) decoding return "Invalid character" error.
so we need to use "uint256" instead of "indexed uint256"

Reproduce the decoding failure for an indexed uint256 event with hexadecimal values from a minimal test case. Trace the event-decoding entry point and existing tests for indexed parameters; done means hexadecimal values from indexed uint256 events decode successfully without the "Invalid character" error, while existing event decoding remains passing.

Written by the indexing model from the issue text.