fix error on no source image

static/poseEditor.js

@@ -208,8 +208,10 @@ function handleMouseUp(event) {
 
 function initializePose(jsonData,w,h) {
   console.log("initializePose");
-  candidate = jsonData.candidate;
-  subset = jsonData.subset;
+  if (jsonData != null) {
+    candidate = jsonData.candidate;
+    subset = jsonData.subset;
+  }
 
   canvas = document.getElementById('canvas');
   ctx = canvas.getContext('2d');