markov: More refined usage of Chain.__touch()

This moves the self.__touch() call around in markov's Chain class such
that it will only access truly available data.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

plugins/markov.py

@@ -52,10 +52,10 @@ class Chain:
         return self.__last_access
 
     def add(self, text: str):
-        self.__touch()
         parts: List[Any] = text.strip().split()
         if not parts:
             return
+        self.__touch()
         self.__load()
         for fragment in windows(parts + [None], self.order + 1):
             head = fragment[0:-1]
@@ -64,15 +64,16 @@ class Chain:
         self.__dirty = True
 
     def get(self, key: str) -> dict[str | None, int]:
-        self.__touch()
         if self.__cache:
             if key in self.__cache:
+                self.__touch()
                 return self.__cache[key]
             else:
                 raise KeyError(key)
         else:
             # Load cache, then return key
             self.__load()
+            self.__touch()
             return self.__cache[key]
 
     def set(self, key: str, value: Mapping[str | None, int]):