Fluent Bit crashes with dummy has flush_on_startup true and has a lua filter

[lecaros]

Bug Report

Describe the bug

Fluent Bit crashes with the following config:

pipeline:
  inputs:
    - name: dummy
      interval_sec: 5
      flush_on_startup: true
  filters:
    - name: lua
      script: transform.lua
      call: test2
      match: "*"
  outputs:
    - name: stdout
      match: '*'

transform.lua

function test2(tag, timestamp, record)
    record["check"] = "checkval"
    return 2, timestamp, record
end

Output:

fluent-bit -c min.yml
Fluent Bit v5.0.4
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


[2026/04/27 17:30:03.061] [ info] [fluent bit] version=5.0.4, commit=29deec9e72, pid=74078
[2026/04/27 17:30:03.062] [ info] [storage] ver=1.1.6, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2026/04/27 17:30:03.062] [ info] [simd    ] NEON
[2026/04/27 17:30:03.062] [ info] [cmetrics] version=2.1.2
[2026/04/27 17:30:03.062] [ info] [ctraces ] version=0.7.1
[2026/04/27 17:30:03.063] [ info] [input:dummy:dummy.0] initializing
[2026/04/27 17:30:03.063] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2026/04/27 17:30:03] [engine] caught signal (SIGSEGV)
ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)ERROR: no debug info in Mach-O executable (make sure to compile with -g; may need to run dsymutil) (-1)[1]    74078 abort      $FBIT_HOME/fluent-bit -c min.yml

To Reproduce

• Steps to reproduce the problem:

Run with the config displayed above. It doesn't reproduce with flush_on_startup: false

Expected behavior

Do not crash.

Your Environment

• Version used: latest from master (commit=29deec9e72)