foundkey-js: make DriveFile.comment nullable

There's a few places in the client code that checks for a null comment,
suggesting this field may be set to null.

packages/foundkey-js/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - foundkey-js is now part of the main FoundKey repo
 - BREAKING: foundkey-js now uses ES2020 modules. Ensure that your version of Node supports them.
+- The `comment` property of `DriveFile` is now nullable. Make sure to check that this property is not `null` before accessing it.
 
 ## 0.0.15 - 2022-07-22
 ### Changed

packages/foundkey-js/src/entities.ts

@@ -117,7 +117,7 @@ export type DriveFile = {
 	size: number;
 	md5: string;
 	blurhash: string;
-	comment: string;
+	comment: string | null;
 	properties: Record<string, any>;
 };