Index: src/org/openstreetmap/josm/plugins/jts/JTSConverter.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/org/openstreetmap/josm/plugins/jts/JTSConverter.java	(revision 34767)
+++ src/org/openstreetmap/josm/plugins/jts/JTSConverter.java	(date 1549214753000)
@@ -90,7 +90,7 @@
         CoordinateSequence coordSeq = convertNodesToCoordinateSequence(way.getNodes());
 
         // TODO: need to check tags to determine whether area or not
-        if (way.isClosed()) {
+        if (way.isClosed() && way.getNodesCount() >= 4) {
             LinearRing ring = new LinearRing(coordSeq, getGeometryFactory());
             return new Polygon(ring, null, getGeometryFactory());
         } else {