diff --git a/src/public/app/widgets/type_widgets/file.js b/src/public/app/widgets/type_widgets/file.ts
similarity index 76%
rename from src/public/app/widgets/type_widgets/file.js
rename to src/public/app/widgets/type_widgets/file.ts
index 5454b7a8f..b4a7d4aeb 100644
--- a/src/public/app/widgets/type_widgets/file.js
+++ b/src/public/app/widgets/type_widgets/file.ts
@@ -1,6 +1,8 @@
 import openService from "../../services/open.js";
 import TypeWidget from "./type_widget.js";
 import { t } from "../../services/i18n.js";
+import type { EventData } from "../../components/app_context.js";
+import type FNote from "../../entities/fnote.js";
 
 const TPL = `
 <div class="note-detail-file note-detail-printable">
@@ -8,7 +10,7 @@ const TPL = `
         .type-file .note-detail {
             height: 100%;
         }
-        
+
         .note-detail-file {
             padding: 10px;
             height: 100%;
@@ -22,21 +24,28 @@ const TPL = `
             margin: 10px;
         }
     </style>
-    
+
     <pre class="file-preview-content"></pre>
-    
+
     <div class="file-preview-not-available alert alert-info">
         ${t("file.file_preview_not_available")}
     </div>
-    
+
     <iframe class="pdf-preview" style="width: 100%; height: 100%; flex-grow: 100;"></iframe>
-    
+
     <video class="video-preview" controls></video>
-    
+
     <audio class="audio-preview" controls></audio>
 </div>`;
 
 export default class FileTypeWidget extends TypeWidget {
+
+    private $previewContent!: JQuery<HTMLElement>;
+    private $previewNotAvailable!: JQuery<HTMLElement>;
+    private $pdfPreview!: JQuery<HTMLElement>;
+    private $videoPreview!: JQuery<HTMLElement>;
+    private $audioPreview!: JQuery<HTMLElement>;
+
     static getType() {
         return "file";
     }
@@ -52,10 +61,10 @@ export default class FileTypeWidget extends TypeWidget {
         super.doRender();
     }
 
-    async doRefresh(note) {
+    async doRefresh(note: FNote) {
         this.$widget.show();
 
-        const blob = await this.note.getBlob();
+        const blob = await this.note?.getBlob();
 
         this.$previewContent.empty().hide();
         this.$pdfPreview.attr("src", "").empty().hide();
@@ -63,7 +72,7 @@ export default class FileTypeWidget extends TypeWidget {
         this.$videoPreview.hide();
         this.$audioPreview.hide();
 
-        if (blob.content) {
+        if (blob?.content) {
             this.$previewContent.show().scrollTop(0);
             this.$previewContent.text(blob.content);
         } else if (note.mime === "application/pdf") {
@@ -72,20 +81,20 @@ export default class FileTypeWidget extends TypeWidget {
             this.$videoPreview
                 .show()
                 .attr("src", openService.getUrlForDownload(`api/notes/${this.noteId}/open-partial`))
-                .attr("type", this.note.mime)
-                .css("width", this.$widget.width());
+                .attr("type", this.note?.mime ?? "")
+                .css("width", this.$widget.width() ?? 0);
         } else if (note.mime.startsWith("audio/")) {
             this.$audioPreview
                 .show()
                 .attr("src", openService.getUrlForDownload(`api/notes/${this.noteId}/open-partial`))
-                .attr("type", this.note.mime)
-                .css("width", this.$widget.width());
+                .attr("type", this.note?.mime ?? "")
+                .css("width", this.$widget.width() ?? 0);
         } else {
             this.$previewNotAvailable.show();
         }
     }
 
-    async entitiesReloadedEvent({ loadResults }) {
+    async entitiesReloadedEvent({ loadResults }: EventData<"entitiesReloaded">) {
         if (loadResults.isNoteReloaded(this.noteId)) {
             this.refresh();
         }