Fix return instead of raise.

[benoit-cty]

Technical changes

• the modify_my_parameters function should return the ParameterNode, but you're not getting the expected error. In the modify_parameters method on line 81, there's a bug in the code. It should raise a ValueError, but instead it returns a ValueError. This means the error is created but not actually thrown, so your code continues executing without the expected error.

• Will close Error not raised when building an erroneous reform #1331

[MattiSG]

@benoit-cty that's a lot of added tests to review, and some checks fail. Could you please clarify if you wrote these tests yourself, or if they were generated by an LLM? If so, which review mechanism did you put in place to ensure that all these tests are relevant and warrant another human to review them? Thank you!

[benjello]

@MattiSG @benoit-cty : this PR fix a recurrent annoying error difficult to grasp.
I think tests are welcom and not to numerous.
However the failing tests are related to retiring windows-server which is a separate issue.

[benoit-cty]

@benoit-cty that's a lot of added tests to review, and some checks fail. Could you please clarify if you wrote these tests yourself, or if they were generated by an LLM? If so, which review mechanism did you put in place to ensure that all these tests are relevant and warrant another human to review them? Thank you!

These tests was indeed added by Copilot to improve the test coverage on the area where @benjello discovered an error.