Bug: Restoring libraries in a project with only one library throws a "object reference not set" error

[laspir]

Type: Bug
TwinPack Version: 1.4.3
TwinCAT Version: 3.1.4029.29
Reproducible: Yes

When "Restore All" is run on a Project with only 1 library

The library is installed but an error message is thrown as shown. This doesn't seem to have any effect on the end result as it is possible to continue working normally afterwards.

If more than one library is added to the project, this error message no longer appears.

Before Restore All

After Restore All

If afterwards the additional libraries are removed again, such that the project once more has only one library, then the error message appears again.

Saving the PLC-Project as .tpzip Archive seems to resolve the issue, until TwinCAT is restarted. Then the issue appears again.

Attached is:

• Two test projects
  -- one with only the test library, where the error occurs
  -- one with two libraries installed, where the error does NOT occur.
• Config.json files for both test projects, to be copied in the .Zeugewerk folder before running the tests.

plcWithError_config.json
workingPlc_config.json
TestProject.zip

[beslst]

This usually works also when restoring a single library, it probably has to do with your specific library, but I can look into that

[laspir]

I tested this in reverse as well, with only the standard Tc2_Math library referenced in the project. This still throws the error, so the issue must be library independent.