Raise OpenContourError on open contour

Author: moyogo

Lib/booleanOperations/exceptions.py

@@ -17,5 +17,9 @@ class InvalidClippingContourError(InvalidContourError):
     """Rased when a 'clipping' contour is not valid"""
 
 
+class OpenContourError(BooleanOperationsError):
+    """Rased when any input contour is open"""
+
+
 class ExecutionError(BooleanOperationsError):
     """Raised when clipping execution fails"""

Lib/booleanOperations/flatten.py

@@ -3,6 +3,7 @@
 from fontTools.misc import bezierTools
 from fontTools.pens.basePen import decomposeQuadraticSegment
 import pyclipper
+from .exceptions import OpenContourError
 
 """
 To Do:
@@ -339,7 +340,8 @@ def endPath(self):
         pass
 
     def addPoint(self, pt, segmentType=None, smooth=False, name=None, **kwargs):
-        assert segmentType != "move"
+        if segmentType == "move":
+            raise OpenContourError("Unhandled open contour")
         if not self._foundStartingPoint and segmentType is not None:
             kwargs['startingPoint'] = self._foundStartingPoint = True
         data = InputPoint(