G7: M03+M05+M07 — cleanup: TypeError guard, dead code removal, None normalization

Why: Three minor cleanup fixes. M03 adds an else branch in set_flood_scope so
unsupported scope types raise TypeError instead of UnboundLocalError. M05 removes
the dead `out_path_len >> 6` shift in update_contact (high bits always zero due
to reader masking) and initializes path_hash_mode=0 explicitly. M07 normalizes
three `return None` paths in get_contacts to return Event(EventType.ERROR, ...)
so callers can rely on the return type always being Event.

Refs: Forensics report findings M03, M05, M07

src/meshcore/commands/contact.py

@@ -43,13 +43,17 @@ class ContactCommands(CommandHandlerBase):
                     logger.debug("Timeout while getting contacts")
                     for future in pending: # cancel all futures
                         future.cancel()
-                    return None
+                    return Event(EventType.ERROR, {"reason": "timeout waiting for contacts"})
 
                 for future in done:
                     event = await future
-                    if event is None or event.type != EventType.NEXT_CONTACT:
-                        for future in pending:
-                            future.cancel()
+                    if event is None:
+                        for f in pending:
+                            f.cancel()
+                        return Event(EventType.ERROR, {"reason": "no event received during contacts retrieval"})
+                    if event.type != EventType.NEXT_CONTACT:
+                        for f in pending:
+                            f.cancel()
                         return event
 
                 futures = []
@@ -64,7 +68,7 @@ class ContactCommands(CommandHandlerBase):
     
         except asyncio.TimeoutError:
             logger.debug(f"Timeout receiving contacts")
-            return None
+            return Event(EventType.ERROR, {"reason": "asyncio timeout receiving contacts"})
         except Exception as e:
             logger.debug(f"Command error: {e}")
             return Event(EventType.ERROR, {"error": str(e)})
@@ -116,7 +120,9 @@ class ContactCommands(CommandHandlerBase):
                     path_hash_mode = int(path.split(":")[1])
                     path = path.split(":")[0].replace(":","")
                 else: # use device one by default
-                    path_hash_mode = contact["out_path_len"] >> 6 # would fallback to previous val
+                    # out_path_len is pre-masked (& 0x3F) in reader.py, so high bits are always 0;
+                    # the actual path_hash_mode is fetched from the device query below.
+                    path_hash_mode = 0
                     res = await self.send_device_query()
                     if not res is None and res.type != EventType.ERROR:
                         if "path_hash_mode" in res.payload:

src/meshcore/commands/messaging.py

@@ -313,6 +313,8 @@ class MessagingCommands(CommandHandlerBase):
         elif isinstance (scope, bytes): # scope has been sent directly as byte
                 logger.debug(f"Directly setting scope to {scope}")
                 scope_key = scope
+        else:
+            raise TypeError(f"set_flood_scope: unsupported scope type {type(scope).__name__}")
 
         logger.debug(f"Setting scope to {scope_key.hex()}")