Remove validator

I don't think we need it because we have a default (empty) map

npe2/_plugin_manager.py

@@ -555,8 +555,6 @@ def properties(self, config_key: str) -> Set[Any]:
         properties_values: Set[Any] = set()
         # Search all manifests for the presence of config key
         for manifest in self._manifests.values():
-            if manifest.properties is None:
-                continue
             if config_key not in manifest.properties:
                 continue
             value = manifest.properties[config_key]

npe2/manifest/schema.py

@@ -126,7 +126,7 @@ class Config:
         exclude=True,
     )
 
-    properties: Optional[Dict[str, Any]] = Field(
+    properties: Dict[str, Any] = Field(
         default={},
         description="Properties for global values."
         "May be appended to by other plugins"
@@ -165,10 +165,6 @@ def author(self) -> Optional[str]:
     def _coerce_none_contributions(cls, value):
         return [] if value is None else value
 
-    @validator("properties", pre=True)
-    def _coerce_none_properties(cls, value):
-        return {} if value is None else value
-
     @root_validator
     def _validate_root(cls, values: dict) -> dict:
         # validate schema version