Fix some wrong type hints and mypy errors (#664)

* Fix too narrow type annotations in emcy and network.
* Return None explicitly where return type expects it.
* Annotate ODVariable and ODArray parent attribute as for ODRecord.

Co-authored-by: Frieder Schüler <frieder.schueler@bizerba.com>

Author: acolomb

canopen/emcy.py

@@ -57,7 +57,7 @@ def reset(self):
 
     def wait(
         self, emcy_code: Optional[int] = None, timeout: float = 10
-    ) -> EmcyError:
+    ) -> Optional[EmcyError]:
         """Wait for a new EMCY to arrive.
 
         :param emcy_code: EMCY code to wait for

canopen/network.py

@@ -141,7 +141,7 @@ def add_node(
         node: Union[int, RemoteNode, LocalNode],
         object_dictionary: Union[str, ObjectDictionary, None] = None,
         upload_eds: bool = False,
-    ) -> RemoteNode:
+    ) -> Union[RemoteNode, LocalNode]:
         """Add a remote node to the network.
 
         :param node:
@@ -167,7 +167,7 @@ def add_node(
 
     def create_node(
         self,
-        node: int,
+        node: Union[int, LocalNode],
         object_dictionary: Union[str, ObjectDictionary, None] = None,
     ) -> LocalNode:
         """Create a local node in the network.

canopen/objectdictionary/__init__.py

@@ -188,6 +188,7 @@ def get_variable(
             return obj
         elif isinstance(obj, (ODRecord, ODArray)):
             return obj.get(subindex)
+        return None
 
 
 class ODRecord(MutableMapping):
@@ -261,7 +262,7 @@ class ODArray(Mapping):
 
     def __init__(self, name: str, index: int):
         #: The :class:`~canopen.ObjectDictionary` owning the record.
-        self.parent = None
+        self.parent: Optional[ObjectDictionary] = None
         #: 16-bit address of the array
         self.index = index
         #: Name of array
@@ -343,7 +344,7 @@ def __init__(self, name: str, index: int, subindex: int = 0):
         #: The :class:`~canopen.ObjectDictionary`,
         #: :class:`~canopen.objectdictionary.ODRecord` or
         #: :class:`~canopen.objectdictionary.ODArray` owning the variable
-        self.parent = None
+        self.parent: Union[ObjectDictionary, ODRecord, ODArray, None] = None
         #: 16-bit address of the object in the dictionary
         self.index = index
         #: 8-bit sub-index of the object in the dictionary

canopen/sdo/base.py

@@ -79,6 +79,7 @@ def get_variable(
             return obj
         elif isinstance(obj, (SdoRecord, SdoArray)):
             return obj.get(subindex)
+        return None
 
     def upload(self, index: int, subindex: int) -> bytes:
         raise NotImplementedError()