corrections based on CR comments

Signed-off-by: David Y Liu <davidyliuliu@gmail.com>

sdk/python/feast/feature_service.py

@@ -64,7 +64,10 @@ def __init__(
             ):
                 self.feature_view_projections.append(feature_grouping.projection)
             else:
-                raise ValueError(f"Unexpected type: {type(feature_grouping)}")
+                raise ValueError(
+                    "The FeatureService {fs_name} has been provided with an invalid type"
+                    f'{type(feature_grouping)} as part of the "features" argument.)'
+                )
 
         self.tags = tags or {}
         self.description = description

sdk/python/feast/feature_view.py

@@ -391,19 +391,27 @@ def infer_features_from_batch_source(self, config: RepoConfig):
 
     def set_projection(self, feature_view_projection: FeatureViewProjection) -> None:
         """
-        Setter for the projection object held by this FeatureView. Performs checks to ensure
-        the projection is consistent with this FeatureView before doing the set.
+        Setter for the projection object held by this FeatureView. A projection is an
+        object that stores the modifications to a FeatureView that is applied to the FeatureView
+        when the FeatureView is used such as during feature_store.get_historical_features.
+        This method also performs checks to ensure the projection is consistent with this
+        FeatureView before doing the set.
 
         Args:
             feature_view_projection: The FeatureViewProjection object to set this FeatureView's
                 'projection' field to.
         """
-        assert feature_view_projection.name == self.name
+        if feature_view_projection.name != self.name:
+            raise ValueError(
+                f"The projection for the {self.name} FeatureView cannot be applied because it differs in name. "
+                f"The projection is named {feature_view_projection.name} and the name indicates which "
+                "FeatureView the projection is for."
+            )
 
         for feature in feature_view_projection.features:
             if feature not in self.features:
                 raise ValueError(
-                    f"The projection for {self.name} cannot be applied because it contains {feature.name} which the"
+                    f"The projection for {self.name} cannot be applied because it contains {feature.name} which the "
                     "FeatureView doesn't have."
                 )