Backport PR #18328: Add missing check for None in Qt toolmanager.

dstansby · meeseeksmachine · commit a93b9fdc90d9 · 2020-08-23T15:43:50.000Z
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
@@ -916,7 +916,8 @@ def add_toolitem(
             self, name, group, position, image_file, description, toggle):
 
         button = QtWidgets.QToolButton(self)
-        button.setIcon(NavigationToolbar2QT._icon(self, image_file))
+        if image_file:
+            button.setIcon(NavigationToolbar2QT._icon(self, image_file))
         button.setText(name)
         if description:
             button.setToolTip(description)
