Adjust type for consistency

Author: jerelmiller

src/core/ApolloClient.ts

@@ -15,6 +15,7 @@ import { execute } from "@apollo/client/link";
 import type { ClientAwarenessLink } from "@apollo/client/link/client-awareness";
 import type { LocalState } from "@apollo/client/local-state";
 import type { MaybeMasked, Unmasked } from "@apollo/client/masking";
+import type { DeepPartial } from "@apollo/client/utilities";
 import { DocumentTransform } from "@apollo/client/utilities";
 import { __DEV__ } from "@apollo/client/utilities/environment";
 import type { VariablesOption } from "@apollo/client/utilities/internal";
@@ -1188,7 +1189,9 @@ export class ApolloClient {
     | ApolloClient.ObservableFragment<Array<TData>> {
     const dataMasking = this.queryManager.dataMasking;
 
-    const mask = (data: TData): TData => {
+    const mask = (
+      data: TData | DeepPartial<TData> | null
+    ): TData | DeepPartial<TData> | null => {
       // The transform will remove fragment spreads from the fragment
       // document when dataMasking is enabled. The `mask` function
       // remains to apply warnings to fragments marked as