Fix ESLint errors and bugs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/specificClass.js

@@ -322,10 +322,11 @@ class Reactor_PFR extends Reactor {
 
   _updateMeasurement(measurementType, value, position, context) {
     switch(measurementType) {
-      case "quantity (oxygen)":
+      case "quantity (oxygen)": {
         let grid_pos = Math.round(position / this.config.length * this.n_x);
         this.state[grid_pos][S_O_INDEX] = value; // naive approach for reconciling measurements and simulation
         break;
+      }
       default:
         super._updateMeasurement(measurementType, value, position, context);
     }