Fixup eslint

Author: eoghanmurray

packages/rrweb-snapshot/src/snapshot.ts

@@ -431,7 +431,7 @@ function serializeNode(
     mirror: Mirror;
     blockClass: string | RegExp;
     blockSelector: string | null;
-    needsMask: boolean;
+    needsMask: boolean | undefined;
     inlineStylesheet: boolean;
     maskInputOptions: MaskInputOptions;
     maskTextFn: MaskTextFn | undefined;
@@ -533,7 +533,7 @@ function getRootId(doc: Document, mirror: Mirror): number | undefined {
 function serializeTextNode(
   n: Text,
   options: {
-    needsMask: boolean;
+    needsMask: boolean | undefined;
     maskTextFn: MaskTextFn | undefined;
     rootId: number | undefined;
   },