Fix Array.from syntax in nonmultiple file upload (#2357)

- Fix Array.from syntax in nonmultiple file upload as Array.from(<non-array or string>) returns an empty array which is the case when a file is selected from an input element (when multiple attribute isn't  supported) which can be found in Array.from(element.files[0]) -> results in an empty array.

src/main/resources/static/js/fileInput.js

@@ -86,7 +86,7 @@ function setupFileInput(chooser) {
     if (element instanceof HTMLInputElement && element.hasAttribute("multiple")) {
       allFiles = isDragAndDrop ? allFiles : [... allFiles, ... element.files];
   } else {
-    allFiles = Array.from(isDragAndDrop ? allFiles : element.files[0]);
+    allFiles = Array.from(isDragAndDrop ? allFiles : [element.files[0]]);
   }
 
     if (!isDragAndDrop) {