diff --git a/mapshaper-gui.js b/mapshaper-gui.js
index 81e3eecd..b6c53158 100644
--- a/mapshaper-gui.js
+++ b/mapshaper-gui.js
@@ -10779,11 +10779,16 @@
       // finish the path if a vertex is selected (but not an interpolated point)
       var finish = hoverVertexInfo?.type == 'vertex';
       if (getLastArcLength(target) < 2) {
-        error$1('Defective path');
+        stop$1('Defective path');
       }
       if (finish && polygonMode()) {
         shapes1 = target.shapes.slice(initialShapeCount);
-        shapes2 = convertClosedPaths(shapes1);
+        try {
+          shapes2 = convertClosedPaths(shapes1);
+        } catch(e) {
+          console.error(e);
+          stop$1('Invalid path');
+        }
       }
       if (shapes2) {
         replaceDrawnShapes(shapes2);
diff --git a/mapshaper.js b/mapshaper.js
index 8c2e2b60..d7c450e7 100644
--- a/mapshaper.js
+++ b/mapshaper.js
@@ -45536,7 +45536,7 @@ ${svg}
     });
   }
 
-  var version = "0.6.83";
+  var version = "0.6.84";
 
   // Parse command line args into commands and run them
   // Function takes an optional Node-style callback. A Promise is returned if no callback is given.