Plot is not generated, if e.g. 'Years to plot' are changed.

In the generation page, http://o3web.test.fedcloud.eu/generation, if one changes for instance "Years to plot", one gets the following error message:

TypeError: errors.find is not a function
handleSubmit
src/components/forms/Generationform.js:307

  304 | event.preventDefault();
  305 | this.saveStateAsCookie();
  306 | const errors = this.state.savedErrors;
> 307 | const error = errors.find(err => err.error !== undefined);
      | ^  308 | if (error !== undefined) {
  309 |     console.error(error.error.message);
  310 |     alert(error.error.message);

Plot is not generated.