Operator '' can not be applied to types 'boolean' and 'number'. ng build --prod

I wonder what might be happening in this case. Every time I try to run the command ng build --prod this error appears saying that it is in the HTML file of one of the components in line 76, it follows that line of error below. To which even removing for testing does not work. Another thing also when I run the ng build command works.

<app-campo-control-erro [mostrarErro]="verificaValidTouchedEpi('quantidade')" mensagemErro="Informe a quantidade."></app-campo-control-erro>

Here is an excerpt of verificaValidTouchedEpi method

verificaValidTouchedEpi(campo: string) {
  return (
    !this.formularioEpi.get(campo).valid &&
    (this.formularioEpi.get(campo).dirty || this.formularioEpi.get(campo).touched)
  );
}

This method is used in other fields of my form plus the error is only giving in that line.