diff --git a/src/kiri/client.js b/src/kiri/client.js
index d05fd738..6b475fbd 100644
--- a/src/kiri/client.js
+++ b/src/kiri/client.js
@@ -28,8 +28,11 @@ let KIRI = self.kiri = self.kiri || {},
 function send(fn, data, onreply, zerocopy) {
     let seq = seqid++;
 
-    running[seq] = { fn:onreply };
-    // console.log('send', data);
+    if (onreply) {
+        // track it only when we expect and can handle a reply
+        running[seq] = { fn:onreply };
+    }
+    // console.log('send', {fn, data, onreply});
 
     try {
         worker.postMessage({
@@ -59,6 +62,7 @@ KIRI.work = {
 
     isBusy: function() {
         let current = 0;
+
         for (let rec of Object.values(running)) {
             if (rec.fn) current++;
         }
@@ -92,7 +96,7 @@ KIRI.work = {
             let now = time(),
                 reply = e.data,
                 record = running[reply.seq],
-                onreply = record.fn;
+                onreply = record ? record.fn : undefined;
 
             // console.log('recv', reply.data)
             if (reply.done) {
@@ -102,7 +106,11 @@ KIRI.work = {
             // calculate and replace recv time
             reply.time_recv = now - reply.time_recv;
 
-            onreply(reply.data, reply);
+            if (onreply) {
+                onreply(reply.data, reply);
+            } else {
+                console.log({unexpected_reply: reply});
+            }
         };
 
         restarting = false;
diff --git a/src/kiri/init.js b/src/kiri/init.js
index 8bad67f0..243baed3 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -248,7 +248,6 @@
                 API.dialog.hide();
                 // cancel slicing
                 API.function.cancel();
-                // if (KIRI.work.isSlicing()) KIRI.work.restart();
                 // kill any poppers in compact mode
                 UC.hidePoppers();
                 // and send an event (used by FDM client)
diff --git a/src/kiri/worker.js b/src/kiri/worker.js
index 49995bb9..4d18136a 100644
--- a/src/kiri/worker.js
+++ b/src/kiri/worker.js
@@ -62,6 +62,7 @@ KIRI.worker = {
                     }
                 }
             }
+            send.done(data.id);
             return;
         }
 
diff --git a/src/mode/cam/ops.js b/src/mode/cam/ops.js
index 4174ae21..28884e0c 100644
--- a/src/mode/cam/ops.js
+++ b/src/mode/cam/ops.js
@@ -266,7 +266,7 @@
 
                 if (!offset) return;
 
-                if (process.camStockClipTo) {
+                if (process.camStockClipTo && stock.x && stock.y && stock.center) {
                     let rect = newPolygon().centerRectangle(stock.center, stock.x, stock.y);
                     offset = cutPolys([rect], offset, slice.z, true);
                 }
@@ -523,7 +523,7 @@
                     CAM.addDogbones(offset, toolDiam / 5);
                 }
 
-                if (process.camStockClipTo) {
+                if (process.camStockClipTo && stock.x && stock.y && stock.center) {
                     let rect = newPolygon().centerRectangle(stock.center, stock.x, stock.y);
                     offset = cutPolys([rect], offset, slice.z, true);
                 }
@@ -719,7 +719,8 @@
             let toolOver = toolDiam * op.step;
             let cutdir = process.camConventional;
             let polys = [];
-            let stockRect = newPolygon().centerRectangle(stock.center, stock.x, stock.y);
+            let stockRect = stock.center && stock.x && stock.y ?
+                newPolygon().centerRectangle(stock.center, stock.x, stock.y) : undefined;
             updateToolDiams(toolDiam);
             if (tabs) {
                 tabs.forEach(tab => {
@@ -746,7 +747,7 @@
                 } else {
                     slice.camLines = [ poly ];
                 }
-                if (process.camStockClipTo) {
+                if (process.camStockClipTo && stockRect) {
                     slice.camLines = cutPolys([stockRect], slice.camLines, z, true);
                 }
                 slice.output()
diff --git a/src/mode/fdm/client.js b/src/mode/fdm/client.js
index 77464d47..28c339a9 100644
--- a/src/mode/fdm/client.js
+++ b/src/mode/fdm/client.js
@@ -64,7 +64,9 @@
         };
 
         for (let key of Object.keys(rangeVars)) {
-            UI[key].range = true;
+            if (UI[key]) {
+                UI[key].range = true;
+            }
         }
 
         function filterSynth() {