solid.loft: added checking for at least 2 wires to prevent segmentation fault. see issue #161. now a ValueError is raised

cadquery/occ_impl/shapes.py

@@ -1214,6 +1214,8 @@ class Solid(Shape, Mixin3D):
             wants to make an infinitely thin shell for a real FreeCADPart.
         """
         # the True flag requests building a solid instead of a shell.
+        if len(listOfWire) < 2:
+            raise ValueError("More than one wire is required")
         loft_builder = BRepOffsetAPI_ThruSections(True, ruled)
 
         for w in listOfWire:

tests/TestCadQuery.py

@@ -259,6 +259,15 @@ class TestCadQuery(BaseTest):
         # the resulting loft had a split on the side, not sure why really, i expected only 3 faces
         self.assertEqual(7, s.faces().size())
 
+    def testLoftWithOneWireRaisesValueError(self):
+        s = Workplane("XY").circle(5)
+        try:
+            s.loft()
+            self.assertFail()
+        except ValueError as e:
+            self.assertEqual(str(e), "More than one wire is required")
+
+
     def testLoftCombine(self):
         """
             test combining a lof with another feature
@@ -2050,4 +2059,4 @@ class TestCadQuery(BaseTest):
         # find solid should return a compund of two solids
         s = r.findSolid()
         self.assertEqual(len(s.Solids()),2)
-        self.assertTrue(isinstance(s,Compound))
+        self.assertTrue(isinstance(s,Compound))