fix/test(serialization): null values in dicts (#168)

specklepy/api/wrapper.py

@@ -21,7 +21,7 @@ class StreamWrapper:
     local account for the server.
 
     ```py
-    from specklepy.api.credentials import StreamWrapper
+    from specklepy.api.wrapper import StreamWrapper
 
     # provide any stream, branch, commit, object, or globals url
     wrapper = StreamWrapper("https://speckle.xyz/streams/3073b96e86/commits/604bea8cc6")

specklepy/serialization/base_object_serializer.py

@@ -198,7 +198,7 @@ class BaseObjectSerializer:
 
         elif isinstance(obj, dict):
             for k, v in obj.items():
-                if isinstance(v, PRIMITIVES):
+                if isinstance(v, PRIMITIVES) or v is None:
                     continue
                 else:
                     obj[k] = self.traverse_value(v)

tests/conftest.py

@@ -102,6 +102,8 @@ def base():
     base = Base()
     base.name = "my_base"
     base.units = "millimetres"
+    base.null_val = None
+    base.null_dict = {"a null val": None}
     base.vertices = [random.uniform(0, 10) for _ in range(1, 120)]
     base.test_bases = [Base(name=i) for i in range(1, 22)]
     base["@detach"] = Base(name="detached base")