Fix use undef

Author: linev

modules/hist2d/RHistPainter.mjs

@@ -149,7 +149,7 @@ class RHistPainter extends RObjectPainter {
                if ((histo.stepx > 1) || (histo.stepy > 1) || (histo.stepz > 1))
                   histo.getBin0 = function(x, y, z) { return Math.floor((x-this.dx)/this.stepx) + this.nx/this.stepx*Math.floor((y-this.dy)/this.stepy) + this.nx/this.stepx*this.ny/this.stepy*Math.floor((z-this.dz)/this.stepz); }
                else
-                  histo.getBin0 = function(x, y, z) { return (x-this.dx) + this.nx*(y-this.dy) + this.nx*this.ny*(z-dz); }
+                  histo.getBin0 = function(x, y, z) { return (x-this.dx) + this.nx*(y-this.dy) + this.nx*this.ny*(z-this.dz); }
 
                histo.getBinContent = function(x, y, z) { return this.fBinContent[this.getBin0(x, y, z)]; }
                histo.getBinError = function(x, y, z) { return Math.sqrt(Math.abs(this.getBinContent(x, y, z))); }