Backend: Remove AssertionError in non-test code.

Author: tristanlabelle

app/backend/src/couchers/email/rendering.py

@@ -213,7 +213,7 @@ def render_plaintext_body(*, blocks: list[EmailBlock], footer: EmailFooter, loc_
                 )
                 concat.append(line)
             case _:
-                raise AssertionError(f"Unexpected email block type: {block.__class__}")
+                raise TypeError(f"Unexpected email block type: {block.__class__}")
         previous_block = block
 
     concat.append("\n\n")
@@ -306,7 +306,7 @@ def render(
                 case ActionBlock():
                     concats.append(self.action_block_template.render(block.__dict__, loc_context))
                 case _:
-                    raise AssertionError(f"Unexpected email block type: {block.__class__}")
+                    raise TypeError(f"Unexpected email block type: {block.__class__}")
 
         # Render the footer
         footer_template_args = footer.to_template_args()

app/backend/src/couchers/notifications/render_email.py

@@ -739,13 +739,14 @@ def get_topic_action_unsubscribe_text(topic_action: NotificationTopicAction) ->
 
 
 def get_topic_key_unsubscribe_text(topic_action: NotificationTopicAction) -> str:
-    assert can_unsubscribe_topic_key(topic_action)
-    # Not localized because the design will change so avoid useless work by translators.
-    match topic_action:
-        case NotificationTopicAction.chat__message:
-            return "this chat (mute)"
-        case _:
-            raise AssertionError(f"No topic-key description for {topic_action}")
+    if can_unsubscribe_topic_key(topic_action):
+        # Not localized because the design will change so avoid useless work by translators.
+        match topic_action:
+            case NotificationTopicAction.chat__message:
+                return "this chat (mute)"
+            case _:
+                pass
+    raise ValueError(f"Topic-action {topic_action} has no unsubscribe text.")
 
 
 def get_email_footer(user: User, notification: Notification, loc_context: LocalizationContext) -> EmailFooter: