[remote_base] Reject unknown protocol names and log a dropped secondary dumper

tests/component_tests/remote_receiver/test_slot_counts.py

@@ -71,6 +71,12 @@ def test_every_registry_name_maps_to_a_protocol_source() -> None:
         assert f"{stem}_protocol.cpp" in sources, name
 
 
+def test_request_protocol_rejects_unknown_names() -> None:
+    """A misspelled protocol would otherwise surface only as a link error."""
+    with pytest.raises(ValueError, match="toshiba"):
+        remote_base.request_protocol("toshiba")
+
+
 def test_dump_list_is_deduplicated_across_forms() -> None:
     dumpers = remote_base.validate_dumpers(["raw", {"raw": None}, "nec", "nec"])
     assert [name for name, _ in dumpers] == ["raw", "nec"]