fix: @ValidateNested() does not work with @Validate(CustomValidator)

[pkvinhu]

Description

When I use @ValidateNested() on its own (together with class-transformer @Type(() => class), works as expected, but when I try to use it with @Validate(CustomValidator), it seems to get skipped straight to the custom validator.

class SomeClass {
    @ApiProperty({ description: 'xyz', type: SomeObject })
    @IsNotEmpty()
    @ValidateNested()
    @Validate(SomeObjectValidator)
    @Type(() => SomeObject)
    someObject: SomeObject;
}

@ValidatorConstraint({ name: 'triggerValidator', async: false })
class SomeObjectValidator implements ValidatorConstraintInterface {
    private validationErrors: string[];

    public readonly attributesKeysMessage = `attribute keys message.`;

    validate(someObject: SomeObject): boolean {
        this.validationErrors = [];
        if (Object.keys(someObject.attributes).length !== 1) {
            this.validationErrors.push(this.attributesKeysMessage);
        }
        return this.validationErrors.length === 0;
    }

    defaultMessage(): string {
        return this.validationErrors[0] || 'Validation failed';
    }
}

class Trigger {
    @ApiProperty({ description: 'Type of some object' })
    @IsNotEmpty()
    type: string;

    @ApiProperty({ description: 'Attributes of some object' })
    @IsNotEmpty()
    attributes: Record<string, unknown>;
}

Expected behavior

When SomeObject is defined without attributes:

{
   type: 'hello world'
   // no attributes
}

it should return a validation error telling me attributes must not be empty, not running the custom validator at all

Actual behavior

The custom validator is run (skipping the @ValidateNested), returning an error Cannot convert undefined or null to object