do not create do action when no widgets present. fix first retraction in part loop in some circumstances

src/kiri/do.js

@@ -95,6 +95,9 @@ kiri.load(function(API) {
     event.on('selection.rotate', (rec) => {
         let type = "rotate";
         let widgets = API.selection.widgets(true);
+        if (!widgets.length) {
+            return;
+        }
         let {x, y, z} = rec;
         if (!(x || y || z)) {
             return;
@@ -120,6 +123,9 @@ kiri.load(function(API) {
             return;
         }
         let widgets = API.selection.widgets(true);
+        if (!widgets.length) {
+            return;
+        }
         let type = "scale";
         pushActions({
             redo: {
@@ -144,6 +150,9 @@ kiri.load(function(API) {
     // move complete (store updated position)
     event.on('mouse.drag.done', () => {
         let widgets = API.selection.widgets(true);
+        if (!widgets.length) {
+            return;
+        }
         let type = "move";
         pushActions({
             redo: {

src/mode/fdm/export.js

@@ -51,7 +51,7 @@
             emitted = 0,
             retracted = 0,
             pos = {x:0, y:0, z:0, f:0},
-            lout = null,
+            lout = {x:0, y:0, z:0},
             last = null,
             zpos = 0,
             bmax = 0,