Fix orphaned debug log and array bounds check

- Remove console.log('hello:') from Measurement.js (#22)
- Add bounds check for peakIndex in predict_class.js (#23)

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

src/predict/predict_class.js

@@ -161,6 +161,11 @@ class Predict {
     //find index of y peak
     const { peak , peakIndex } = this.getLocalPeak(curve.y);
 
+    // Guard against invalid peakIndex (e.g. empty array returns -1)
+    if (peakIndex < 0 || peakIndex >= curve.x.length) {
+      return { yPeak: null, x: null, xProcent: null };
+    }
+
     // scale the x value to procentual value
     const yPeak = peak;
     const x = curve.x[peakIndex];