Example Plugin Engine: [ADIOS2 EXCEPTION] <Helper> <adiosType> <CheckForNullPtr> : found null pointer for variable in call to Engine::Get

[tybulut]

Describe the bug
On top of mater on github repository, compiled from source code on Debian Linux.
examplePluginEngine_write succeeds
examplePluginEngine_read fails with:

variable does not exist
Engine "TestPlugin" destroyed without a prior Close().
This may have negative consequences.
Invalid argument exception, STOPPING PROGRAM
[Mon Feb 20 16:14:26 2023] [ADIOS2 EXCEPTION] : found null pointer for variable in call to Engine::Get

To Reproduce
A minimal reproducible example is preferred.
Or Steps to reproduce the behavior:

1. Built latest git master branch
2. Run examplePluginEngine_read
3. Run examplePluginEngine_write
4. See error on terminal

Expected behavior
Success on terminal:
data was read correctly!

Desktop (please complete the following information):

• OS/Platform: Debian 11.6
• Build
  ADIOS2 build configuration:
  ADIOS Version: 2.9.0
  C++ Compiler : GNU 10.2.1
  /usr/bin/c++

Fortran Compiler : GNU 10.2.1
/usr/bin/f95

Installation prefix: /media/src/york.ac.uk/usr
bin: bin
lib: lib
include: include
cmake: lib/cmake/adios2
python: lib/python3.9/site-packages

Features:
Library Type: shared
Build Type: Release
Testing: ON
Examples: ON
Build Options:
BP5 : ON
DataMan : OFF
DataSpaces: OFF
HDF5 : ON
HDF5_VOL : OFF
MHS : ON
SST : ON
CUDA : OFF
Fortran : ON
MPI : ON
Python : OFF
Blosc2 : OFF
BZip2 : ON
LIBPRESSIO: OFF
MGARD : OFF
PNG : OFF
SZ : OFF
ZFP : OFF
DAOS : OFF
IME : OFF
O_DIRECT : ON
Sodium : OFF
Catalyst : OFF
SysVShMem : ON
UCX : OFF
ZeroMQ : OFF
Profiling : ON
Endian_Reverse: OFF
GPU_Support: OFF
AWSSDK : OFF
RDMA Transport for Staging: Unconfigured
-- Configuring done

Additional context
None

Following up

[caitlinross]

I was able to reproduce. I thought this example was being used in one of the CI tests, so I'll need to also figure out why either it's not being run or the error isn't being reported by CI.

[tybulut]

I verified / tested the PR#3499 successfully on my setup. Thanks!