skip over anchor less axes:

- in case some dummy axes were included in user layout.
  (e.g. someone layout = {xaxis: {}, scene: {xaxis: {}}} in
  a 3d-only graph.

Author: etpinard

src/plots/cartesian/axes.js

@@ -1171,7 +1171,7 @@ axes.getSubplots = function(gd, ax) {
         if(subplots.indexOf(sp) === -1) subplots.push(sp);
     }
 
-    // look for subplots in the axes/anchors, so that we at least draw all axes
+    // look for subplots in the xes/anchors, so that we at least draw all axes
     var axesList = axes.list(gd, '', true);
 
     function hasAx2(sp, ax2) {
@@ -1186,23 +1186,20 @@ axes.getSubplots = function(gd, ax) {
                 ax2.anchor,
             ax3 = axes.getFromId(gd, ax3Id);
 
-        // if a free axis is already represented in the data, ignore it
+        // look if ax2 is already represented in the data
         var foundAx2 = false;
         for(j = 0; j < subplots.length; j++) {
             if(hasAx2(subplots[j], ax2)) {
                 foundAx2 = true;
                 break;
             }
         }
+
+        // ignore free axes that already represented in the data
         if(ax2.anchor === 'free' && foundAx2) continue;
 
-        if(!ax3) {
-            console.log([
-                'Warning: couldnt find anchor', ax3Id,
-                'for axis', ax2._id
-            ].join(' '));
-            return;
-        }
+        // ignore anchor-less axes
+        if(!ax3) continue;
 
         sp = (ax2Letter === 'x') ?
             ax2._id + ax3._id :