Fixing Issue 1580

Author: NishkalankBezawada

src/controls/listItemAttachments/utilities.ts

@@ -34,8 +34,7 @@ export default class utilities {
    */
   public GetFileImageUrl(_file: IListItemAttachmentFile): Promise<string> {
     let _fileImageUrl: string = DOCICONURL_GENERIC;
-    const _fileTypes = _file.FileName.split('.');
-    const _fileExtension = _fileTypes[1];
+    const _fileExtension = _file.FileName.substr(_file.FileName.lastIndexOf('.') + 1);
 
    if ( !_fileExtension){
      return Promise.resolve(_fileImageUrl);