NestJS Resend API Key - Header is not defined

Question

I have a Email module that a created to use to send e-mail's and i use Resend API to send those e-mail's... The error started when i change my EmailService... So now i call InterfaceEmailService, and EmailService implements this interface. But when i try to run the project, the error occurs...

email.module

@Module({
    imports: [ConfigModule.forRoot()],
    providers: [
        {
            provide: 'IEmailService',
            useClass: EmailService,
        },
    ],
    exports: ['IEmailService'],
})
export class EmailModule { }

email.service

@Injectable()
export class EmailService implements IEmailService {
    private readonly resendPrivateKey = this.configService.get<string>('RESEND_API_KEY', '');
    private readonly resend = new Resend(this.resendPrivateKey);
    private readonly fromEmail = '[email protected]';

    constructor(private readonly configService: ConfigService) { }

    async sendMail(to: string, subject: string, html: string): Promise<void> {
        try {
            await this.resend.emails.send({
                from: this.fromEmail,
                to: to,
                subject: subject,
                html: html,
            });
        } catch (error: any) {
            console.error(error);
        }
    }
}

interface.email.service

export interface IEmailService {
    sendMail(to: string, subject: string, html: string): Promise<void>;
}

I try to change my .env, change imports...