Object reference not set to an instance of an object.

Good morning,
I have a PowerShell module at work with almost 400 functions. Recently I switched from PSScriptAnalyzer version 1.13.0 to version 1.21.0, fixed a lot of problems, but I have one left. On random functions I get the error:

Exception: Object reference not set to an instance of an object.

If I use the Invoke-ScriptAnalyzer function with the -Verbose switch, the error does not occur. I discovered this by accident while looking for which function is causing the error.

Please advise how to trace the cause.
Somewhere I found information that this can be caused by the Export-ModuleMember function, but I don't want to get rid of it because I would have to fiddle with building the manifest file and that's how Psake does it for me.

For building and checking a powershell module I use
TeamCity and
Psake = '4.9.0'
Pester = '5.3.3'
BuildHelpers = '2.0.16'
PSScriptAnalyzer = '1.21.0'
PSDepend = '0.3.8'

Comienza reproduciendo el error de referencia nula con el módulo de PowerShell indicado y PSScriptAnalyzer 1.21.0, comparando ejecuciones normales y con -Verbose de Invoke-ScriptAnalyzer. Reduce el fallo a una función o una operación específica del analizador usando las versiones del módulo y de la herramienta de compilación indicadas en el informe; se considera terminado cuando se identifica la causa y se evita la excepción sin requerir una salida detallada.