small fix

app/models.py

@@ -775,14 +775,17 @@ class User(HashidMixin, UserMixin, db.Model):
     #endregion Profile Privacy settings
 
     def follow_corpus(self, corpus, role=None):
+        if self.is_following_corpus(corpus):
+            return
         if role is None:
             r = CorpusFollowerRole.query.filter_by(default=True).first()
         cfa = CorpusFollowerAssociation(corpus=corpus, role=r, follower=self)
         db.session.add(cfa)
 
     def unfollow_corpus(self, corpus):
-        if self.is_following_corpus(corpus):
-            self.followed_corpora.remove(corpus)
+        if not self.is_following_corpus(corpus):
+            return
+        self.followed_corpora.remove(corpus)
 
     def is_following_corpus(self, corpus):
         return corpus in self.followed_corpora