Attr default value can be modified by reference

[Graphmaxer]

Environment

No response

Reproduction

• Create a model with a field this.attr(() => ({}), for example: parameters: this.attr(() => {}),
• Create a new instance of this model and add an attribute to this value, for example: 'model.parameters.a = 1;`
• All new instances of this model will have this new attribute a inside parameters by default

Describe the bug

The attr field type should create a copy of the default value to avoid modifying it by reference

Additional context

No response

Logs

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