colors: Do not crash on invalid colors

When colors are inferred from variable's attributes, something might go
wrong (i.e. invalid value). Instead of crashing, default colors are now
used.

Author: astaric

Orange/data/variable.py

@@ -471,10 +471,11 @@ def number_of_decimals(self):
     @property
     def colors(self):
         if self._colors is None:
-            if "colors" in self.attributes:
+            try:
                 col1, col2, black = self.attributes["colors"]
                 self._colors = (hex_to_color(col1), hex_to_color(col2), black)
-            else:
+            except (KeyError, ValueError):
+                # Stored colors were not available or invalid, use defaults
                 self._colors = ((0, 0, 255), (255, 255, 0), False)
         return self._colors
 

Orange/widgets/data/tests/test_owcolor.py

@@ -19,3 +19,11 @@ def test_reuse_old_settings(self):
 
         w = self.create_widget(OWColor, reset_default_settings=False)
         self.send_signal("Data", self.iris, widget=w)
+
+    def test_invalid_input_colors(self):
+        a = ContinuousVariable("a")
+        a.attributes["colors"] = "invalid"
+        a.colors
+        t = Table(Domain([a]))
+
+        self.send_signal("Data", t)