Slight indexing perf improvement

src/cache-manager.ts

@@ -1,4 +1,4 @@
-import { Notice } from 'obsidian'
+import { Notice, TFile } from 'obsidian'
 import {
   type DocumentRef,
   getTextExtractor,
@@ -32,8 +32,9 @@ import { settings } from './settings'
 async function getAndMapIndexedDocument(
   path: string
 ): Promise<IndexedDocument> {
-  const file = app.vault.getFiles().find(f => f.path === path)
+  const file = app.vault.getAbstractFileByPath(path)
   if (!file) throw new Error(`Invalid file path: "${path}"`)
+  if (!(file instanceof TFile)) throw new Error(`Not a TFile: "${path}"`)
   let content: string | null = null
 
   const extractor = getTextExtractor()