In the installer log file, "Null" value gets suffixed to "Installation: Successful" Summary when a warning message is encountered during installation

[RMPujar2023]

During an installation using IA 2020 SP2, we are leveraging "CustomError.WARNING" option in our custom code to update the installer log with a WARNING message when an action does not happen.

An observation found with this action is, in the installer log file under Summary section, there is the following entry:

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Summary
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Installation: Successful null

78 Successes
1 Warnings
0 NonFatalErrors
0 FatalErrors

Action Notes:

None

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How to determine what is causing the "null" value after the "Installation : Successful" action in the log file.

If there are no warnings then it displays without the "null" value.

Summary
-------

Installation: Successful.

77 Successes
0 Warnings
0 NonFatalErrors
0 FatalErrors

Action Notes:

None

Can you let me know where and what causes this "null" entry in the Summary?
How can it be removed/modified to display meaningful information.