[widgets][toolchaineditor] patching ValueError with KeyError for BlockType classmethod

beat/editor/widgets/toolchaineditor.py

@@ -762,8 +762,8 @@ class BlockType(Enum):
     def from_name(cls, name):
         try:
             return cls[name]
-        except ValueError:
-            raise ValueError("{} is not a valid block type".format(name))
+        except KeyError:
+            raise KeyError("{} is not a valid block type".format(name))
 
 
 class Block(QGraphicsObject):