Merge pull request #10210 from Ultimaker/CURA-8412_fix_contextmenu_snapshot_crash

[CURA-8412] Part of fix for crash on context menu open + click on slice.

cura/PreviewPass.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020 Ultimaker B.V.
+# Copyright (c) 2021 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
 from typing import Optional, TYPE_CHECKING, cast, List
@@ -74,6 +74,7 @@ class PreviewPass(RenderPass):
                 self._shader.setUniformValue("u_faceId", -1)  # Don't render any selected faces in the preview.
             else:
                 Logger.error("Unable to compile shader program: overhang.shader")
+                return
 
         if not self._non_printing_shader:
             self._non_printing_shader = OpenGL.getInstance().createShaderProgram(Resources.getPath(Resources.Shaders, "transparent_object.shader"))

cura/Snapshot.py

@@ -93,7 +93,7 @@ class Snapshot:
             pixel_output = preview_pass.getOutput()
             try:
                 min_x, max_x, min_y, max_y = Snapshot.getImageBoundaries(pixel_output)
-            except ValueError:
+            except (ValueError, AttributeError):
                 return None
 
             size = max((max_x - min_x) / render_width, (max_y - min_y) / render_height)