fix: added exceptions

src/common/actionflow.py

@@ -1,4 +1,6 @@
 from abc import abstractmethod, ABCMeta
+class Unavailable(BaseException): pass
+class NotAllowed(BaseException): pass
 
 class Action(BaseException, metaclass=ABCMeta):
     def __init__(self, *args):
@@ -26,10 +28,11 @@ class ActionFlow:
     def do(self, action: str):
         index = self.indices.get(action)
         assert index is not None
-
-        if self.on[index] is not None:
-            value = self.actions[index].prepare()
-            self.on[index] = value
+        
+        if self.on[index]: raise Unavailable(action)
+        if self.on[index] is None: raise NotAllowed(action)
+        value = self.actions[index].prepare()
+        self.on[index] = bool(value)
 
     def react(self):
         for index in self.indices.values():
@@ -43,7 +46,7 @@ class ActionFlow:
         assert index is not None
         return index
     
-    def allow(self, kind, value: bool):
+    def allow(self, kind, value=True):
         index = self.index(kind)
         self.on[index] = False if value else None
 
@@ -65,4 +68,4 @@ class ActionFlow:
 
     def capabilities(self) -> dict[str, bool]:
         items = self.indices.items()
-        return { k: self.on[v] == False for k, v in items }
+        return { k: not self.on[v] for k, v in items if self.on[v] is not None }