diff --git a/examples/data/breaks.csv b/examples/data/breaks.csv
new file mode 100644
index 0000000..80ed925
--- /dev/null
+++ b/examples/data/breaks.csv
@@ -0,0 +1,20 @@
+Family,Sample0,Sample1,Sample2,Sample3,Sample4,Sample5,Sample6,Sample7,Sample8,Sample9,Sample10,Sample11,Sample12,Sample13,Sample14,Sample15,Sample16,Sample17,Sample18,Sample19
+Crenarchaeota,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Euryarchaeota,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Actinobacteria,44,285,2,0,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Aquificae,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Bacteroidetes,5,58,6,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Cyanobacteria,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Elusimicrobia,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Firmicutes,164,234,8,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Fusobacteria,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Proteobacteria,3,6,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0
+Spirochaetes,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Tenericutes,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Dictyosteliales,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Entamoebidae,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Fungi,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Metazoa,0,0,55,0,51,40,47,5,8,10,48,8,59,8,64,8,8,8,55,38
+Pyrenomonadales,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Viridiplantae,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+Nidovirales,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
diff --git a/examples/heatmap.html b/examples/heatmap.html
index 281cc2e..3b16105 100644
--- a/examples/heatmap.html
+++ b/examples/heatmap.html
@@ -13,9 +13,9 @@
         <div id="heatmap"></div>
         <button id="cluster">Cluster!</button>
 
-        <script type="module">
+        <script>
 
-            d3.csv('data/dendrogram.csv')
+            d3.csv('data/breaks.csv')
                 .then(function(data) {
 
                     let grid = [];
diff --git a/src/heatmap/heatmap.ts b/src/heatmap/heatmap.ts
index 01a341a..7693678 100644
--- a/src/heatmap/heatmap.ts
+++ b/src/heatmap/heatmap.ts
@@ -8,7 +8,7 @@ import {HeatmapData, HeatmapElement, HeatmapValue} from "./input";
 import Reorderer from "../reorder/reorderer";
 import MoloReorderer from "../reorder/moloReorderer";
 
-class Heatmap {
+export class Heatmap {
     private element: HTMLElement;
     private settings: HeatmapSettings;
 
@@ -82,12 +82,13 @@ class Heatmap {
 
         let molo: Reorderer = new MoloReorderer();
 
+        console.log("Reorder rows");
         // Create a new ClusterElement for every row that exists. This ClusterElement keeps track of an array of numbers that correspond to a row's values.
         let rowElements: ClusterElement[] = this.rows.map((el, idx) => new ClusterElement(this.values[idx].filter(val => val.rowId == el.id).map(x => x.value), el.id!));
         // Now we perform a depth first search on the result in order to find the order of the values
         let rowOrder: number[] = this.determineOrder(molo.reorder(clusterer.cluster(rowElements)), (id: string) => this.rowMap.get(id)!.idx!);
 
-
+        console.log("Reorder columns");
         // Create a new ClusterElement for every column that exists.
         let columnElements: ClusterElement[] = this.columns.map((el, idx) => new ClusterElement(this.values.map(col => col[idx].value), el.id!));
         let columnOrder: number[] = this.determineOrder(clusterer.cluster(columnElements), (id: string) => this.columnMap.get(id)!.idx!);
diff --git a/src/reorder/moloReorderer.ts b/src/reorder/moloReorderer.ts
index 2a44845..f8d42f0 100644
--- a/src/reorder/moloReorderer.ts
+++ b/src/reorder/moloReorderer.ts
@@ -60,7 +60,7 @@ export default class MoloReorderer implements Reorderer {
             let leftMin = this.nodeMinMap.get(leftSorted);
             let rightMin = this.nodeMinMap.get(rightSorted);
 
-            if (!leftMin || !rightMin) {
+            if (leftMin === undefined || rightMin === undefined) {
                 throw "One of the recursive calls to sort a subtree did not yield a minimum value.";
             }