fix: remove redundant dataTransfer null check

Author: Roland Groza

src/file-selector.spec.ts

@@ -12,6 +12,11 @@ it('should return an empty array if the passed arg is not what we expect', async
     expect(files).toHaveLength(0);
 });
 
+it('should return an empty array if drag event', async () => {
+    const files = await fromEvent({});
+    expect(files).toHaveLength(0);
+});
+
 it('should return the evt {target} {files} if the passed event is an input evt', async () => {
     const name = 'test.json';
     const mockFile = createFile(name, {ping: true}, {

src/file-selector.ts

@@ -19,7 +19,7 @@ const FILES_TO_IGNORE = [
  * @param evt
  */
 export async function fromEvent(evt: Event | any): Promise<(FileWithPath | DataTransferItem)[]> {
-    if (isObject<DragEvent>(evt) && isDataTransfer(evt)) {
+    if (isObject<DragEvent>(evt) && isDataTransfer(evt.dataTransfer)) {
         return getDataTransferFiles(evt.dataTransfer, evt.type);
     } else if (isChangeEvt(evt)) {
         return getInputFiles(evt);
@@ -30,7 +30,7 @@ export async function fromEvent(evt: Event | any): Promise<(FileWithPath | DataT
 }
 
 function isDataTransfer(value: any): value is DataTransfer {
-    return isObject(value.dataTransfer);
+    return isObject(value);
 }
 
 function isChangeEvt(value: any): value is Event {
@@ -52,11 +52,7 @@ async function getFsHandleFiles(handles: any[]) {
 }
 
 
-async function getDataTransferFiles(dt: DataTransfer | null, type: string) {
-    if (dt === null) {
-        return [];
-    }
-
+async function getDataTransferFiles(dt: DataTransfer, type: string) {
     // IE11 does not support dataTransfer.items
     // See https://developer.mozilla.org/en-US/docs/Web/API/DataTransfer/items#Browser_compatibility
     if (dt.items) {