Geometry: fix error on the first right click in the profile plot (water limits not yet cached)

src/Model/Geometry/ProfileXYZ.py

@@ -17,6 +17,7 @@
 # -*- coding: utf-8 -*-
 
 import queue
+import types
 import random
 import logging
 import numpy as np
@@ -806,7 +807,11 @@ class ProfileXYZ(Profile, SQLSubModel):
         return poly
 
     def wet_points(self, z):
-        left, right = self.get_water_limits(z)
+        limits = self.get_water_limits(z)
+
+        if isinstance(limits, types.GeneratorType):
+            limits = next(limits)
+        left, right = limits
 
         points = list(filter(lambda p: p.z < z, self._points))
         points = [left] + points + [right]