fix(visualization): NAN value is encountered when min and max are the…

… same (#147)

* fixed dataVisualization from displaying black region when there is 1 value

* fix: rgbToHex is not defined

* fix: return the actual toColor hex

---------

Co-authored-by: alessandroboarotto <alessandro.boarotto@redder.it>
Co-authored-by: Mustafa Omar <themustafaomar@gmail.com>

src/js/dataVisualization.js

@@ -50,6 +50,10 @@ class DataVisualization {
   }
 
   getValue(value) {
+    if (this.min === this.max) {
+      return `#${this._toColor.join('')}`
+    }
+
     let hex, color = '#'
 
     for (var i = 0; i < 3; i++) {