FIX: do not try to interpolate empty paths

Author: rcomer

lib/matplotlib/path.py

@@ -681,7 +681,7 @@ def interpolated(self, steps):
         Path
             The interpolated path.
         """
-        if steps == 1:
+        if steps == 1 or len(self) == 0:
             return self
 
         if self.codes is not None and self.MOVETO in self.codes[1:]:

lib/matplotlib/tests/test_path.py

@@ -617,3 +617,8 @@ def test_interpolated_moveto_closepoly():
 
     np.testing.assert_allclose(result.vertices, expected_vertices)
     np.testing.assert_array_equal(result.codes, expected_codes)
+
+
+def test_interpolated_empty_path():
+    path = Path(np.zeros((0, 2)))
+    assert path.interpolated(42) is path