JHipster .NET Core: Entity regeneration fails after JDL import with --single-entity

[jfcode27]

Overview of the issue

The error "Cannot read properties of undefined (reading 'length')" occurs when regenerating an entity using jhipster-dotnetcore:entity only for entities that have relationships. This happens after importing a JDL file and attempting to regenerate a specific entity with the --single-entity flag.

Motivation for or Use Case

I need to regenerate an entity in my JHipster .NET Core project while maintaining existing entities and introducing modifications from a JDL file.

Reproduce the error

1. Import a JDL file using: jhipster-dotnetcore import-jdl jdl.jh --json-only
2. Run the entity regeneration command for a specific entity: jhipster-dotnetcore entity EntityName --single-entity

Expected behavior

The entity should be regenerated using the information from the JDL file, while preserving existing entities and configurations.

JHipster Version(s)

• "generator-jhipster": "8.1.0",
  "generator-jhipster-dotnetcore": "^4.1.0"

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