Fix

src/app/services/file/file-to-base64.service.ts

@@ -0,0 +1,19 @@
+import { Injectable } from '@angular/core';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class FileToBase64Service {
+
+  constructor() { }
+
+  convert(file) {
+    return new Promise((resolve, reject) => {
+      const reader = new FileReader();
+      reader.readAsDataURL(file);
+      reader.onload = () => resolve(reader.result);
+      reader.onerror = error => reject(error);
+    });
+  
+  }
+}