filter_type_converter: fix error handling after flb_log_event_decoder_next

[nokute78]

This patch is to fix error verification after flb_log_event_decoder_next.
See also #7636

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Testing
Before we can approve your change; please submit the following in a comment:

• [N/A] Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• [N/A] Run local packaging test showing all targets (including any new ones) build.
• [N/A] Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• [N/A] Documentation required for this feature

Backporting

• [N/A] Backport to latest stable release.

Debug/Valgrind output

$ valgrind --leak-check=full bin/flb-rt-filter_type_converter 
==16367== Memcheck, a memory error detector
==16367== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==16367== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==16367== Command: bin/flb-rt-filter_type_converter
==16367== 
Test str_to_int...                              [ OK ]
Test str_to_float...                            [ OK ]
Test str_to_hex...                              [ OK ]
Test int_to_str...                              [ OK ]
Test int_to_float...                            [ OK ]
Test str<->int...                               [ OK ]
Test nest_key...                                [ OK ]
SUCCESS: All unit tests have passed.
==16367== 
==16367== HEAP SUMMARY:
==16367==     in use at exit: 0 bytes in 0 blocks
==16367==   total heap usage: 10,745 allocs, 10,745 frees, 5,448,672 bytes allocated
==16367== 
==16367== All heap blocks were freed -- no leaks are possible
==16367== 
==16367== For lists of detected and suppressed errors, rerun with: -s
==16367== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[github-actions]

This PR is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[nokute78]

Rebased using current master

[github-actions]

This PR is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[github-actions]

This PR is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[github-actions]

This PR is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 10 days.