code: function handleEvent_(evt) {
    if (evt.type != 'pointermove' || evt.dragging) {
      return true;
    }
  
    const helpMsg = this.sketchFeature === null ? this.startMsg : this.continueMsg;
    if (!helpMsg) {
      throw new Error('Missing helpMsg');
    }
  
    if (this.displayHelpTooltip_) {
      if (!this.helpTooltipElement_) {
        throw new Error('Missing helpTooltipElement');
      }
      if (!this.helpTooltipOverlay_) {
        throw new Error('Missing helpTooltipOverlay');
      }
      olDom.removeChildren(this.helpTooltipElement_);
      this.helpTooltipElement_.appendChild(helpMsg);
      this.helpTooltipOverlay_.setPosition(evt.coordinate);
    }
  
    return true;
  }
docs: Handle map browser event.
  @param {import("ol/MapBrowserEvent.js").default} evt Map browser event.
  @return {boolean} `false` if event propagation should be stopped.
  @private
  @hidden
  @this {Measure}