sometimes label index is the only MOVETO

rcomer · rcomer · commit 07f694dc3f0e · 2023-07-12T12:57:34.000+01:00
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -370,7 +370,10 @@ def _split_path_and_get_label_rotation(self, path, idx, screen_pos, lw, spacing=
         # path always starts with a MOVETO, and we consider there's an implicit
         # MOVETO (closing the last path) at the end.
         movetos = (codes == Path.MOVETO).nonzero()[0]
-        start = movetos[movetos < idx][-1]
+        try:
+            start = movetos[movetos < idx][-1]
+        except IndexError:
+            start = idx
         try:
             stop = movetos[movetos > idx][0]
         except IndexError:
