Apply suggestions from code review

Co-authored-by: Sigrid Huemer <32902192+s1gr1d@users.noreply.github.com>

Author: onurtemizkan

packages/node/src/integrations/tracing/firebase/otel/patches/firestore.ts

@@ -51,9 +51,8 @@ export function patchFirestore(
   config: FirebaseInstrumentationConfig,
 ): InstrumentationNodeModuleDefinition {
   // eslint-disable-next-line @typescript-eslint/no-empty-function
-  const defaultFirestoreSpanCreationHook: FirestoreSpanCreationHook = () => {};
-
-  let firestoreSpanCreationHook: FirestoreSpanCreationHook = defaultFirestoreSpanCreationHook;
+  // Setting an empty function as a default
+  let firestoreSpanCreationHook: FirestoreSpanCreationHook = () => {};
   const configFirestoreSpanCreationHook = config.firestoreSpanCreationHook;
 
   if (typeof configFirestoreSpanCreationHook === 'function') {

packages/node/src/integrations/tracing/firebase/otel/types.ts

@@ -46,7 +46,7 @@ export interface DocumentReference<T = DocumentData, U extends DocumentData = Do
       settings: FirestoreSettings;
     };
   };
-  type: string; // 'collection' or 'document'
+  type: 'collection' | 'document' | string;
   path: string;
   parent: CollectionReference<T, U>;
 }