Program: 70034
Project: 70034
Buggy source:
/** 
 * @see org.olat.modules.bc.commands.FolderCommand#execute(org.olat.modules.bc.components.FolderComponent,org.olat.core.gui.UserRequest,org.olat.core.gui.control.WindowControl,org.olat.core.gui.translator.Translator)
 */
public Controller execute(FolderComponent folderComponent,UserRequest ureq,WindowControl wControl,Translator translator){
  String pos=ureq.getParameter(ListRenderer.PARAM_CONTENTEDITID);
  if (!StringHelper.containsNonWhitespace(pos)) {
    status=FolderCommandStatus.STATUS_FAILED;
    getWindowControl().setError(translator.translate("String_Node_Str"));
    return null;
  }
  status=FolderCommandHelper.sanityCheck(wControl,folderComponent);
  if (status == FolderCommandStatus.STATUS_SUCCESS) {
    currentItem=folderComponent.getCurrentContainerChildren().get(Integer.parseInt(pos));
    status=FolderCommandHelper.sanityCheck2(wControl,folderComponent,ureq,currentItem);
  }
  if (status == FolderCommandStatus.STATUS_FAILED) {
    return null;
  }
  status=FolderCommandHelper.fileEditSanityCheck(currentItem);
  if (status == FolderCommandStatus.STATUS_FAILED) {
    logWarn("String_Node_Str" + folderComponent.getCurrentContainerPath() + "String_Node_Str"+ currentItem.getName(),null);
    getWindowControl().setError(translator.translate("String_Node_Str"));
    return null;
  }
  if (MetaInfoHelper.isLocked(currentItem,ureq)) {
    List<String> lockedFiles=Collections.singletonList(currentItem.getName());
    String msg=MetaInfoHelper.renderLockedMessageAsHtml(translator,folderComponent.getCurrentContainer(),lockedFiles);
    List<String> buttonLabels=Collections.singletonList(translator.translate("String_Node_Str"));
    lockedFiledCtr=activateGenericDialog(ureq,translator.translate("String_Node_Str"),msg,buttonLabels,lockedFiledCtr);
    return null;
  }
  String relFilePath="String_Node_Str" + currentItem.getName();
  if (!folderComponent.getCurrentContainerPath().equals("String_Node_Str")) {
    relFilePath=folderComponent.getCurrentContainerPath() + relFilePath;
  }
  VFSContainer writableRootContainer=folderComponent.getRootContainer();
  Object[] result=VFSManager.findWritableRootFolderFor(writableRootContainer,relFilePath);
  if (result != null) {
    writableRootContainer=(VFSContainer)result[0];
    relFilePath=(String)result[1];
  }
 else {
    relFilePath=currentItem.getName();
    writableRootContainer=folderComponent.getCurrentContainer();
  }
  if (relFilePath.endsWith("String_Node_Str") || relFilePath.endsWith("String_Node_Str")) {
    CustomLinkTreeModel customLinkTreeModel=folderComponent.getCustomLinkTreeModel();
    if (customLinkTreeModel != null) {
      editorc=WysiwygFactory.createWysiwygControllerWithInternalLink(ureq,getWindowControl(),writableRootContainer,relFilePath,true,customLinkTreeModel);
      ((HTMLEditorController)editorc).setNewFile(false);
    }
 else {
      editorc=WysiwygFactory.createWysiwygController(ureq,getWindowControl(),writableRootContainer,relFilePath,true);
      ((HTMLEditorController)editorc).setNewFile(false);
    }
  }
 else {
    editorc=new PlainTextEditorController(ureq,getWindowControl(),(VFSLeaf)currentItem,"String_Node_Str",true,false,null);
  }
  listenTo(editorc);
  putInitialPanel(editorc.getInitialComponent());
  return this;
}

Fixed version (ground truth):
/** 
 * @see org.olat.modules.bc.commands.FolderCommand#execute(org.olat.modules.bc.components.FolderComponent,org.olat.core.gui.UserRequest,org.olat.core.gui.control.WindowControl,org.olat.core.gui.translator.Translator)
 */
public Controller execute(FolderComponent folderComponent,UserRequest ureq,WindowControl wControl,Translator translator){
  String pos=ureq.getParameter(ListRenderer.PARAM_CONTENTEDITID);
  if (!StringHelper.containsNonWhitespace(pos)) {
    status=FolderCommandStatus.STATUS_FAILED;
    getWindowControl().setError(translator.translate("String_Node_Str"));
    return null;
  }
  status=FolderCommandHelper.sanityCheck(wControl,folderComponent);
  if (status == FolderCommandStatus.STATUS_SUCCESS) {
    currentItem=folderComponent.getCurrentContainerChildren().get(Integer.parseInt(pos));
    status=FolderCommandHelper.sanityCheck2(wControl,folderComponent,ureq,currentItem);
  }
  if (status == FolderCommandStatus.STATUS_FAILED) {
    return null;
  }
  status=FolderCommandHelper.fileEditSanityCheck(currentItem);
  if (status == FolderCommandStatus.STATUS_FAILED) {
    logWarn("String_Node_Str" + folderComponent.getCurrentContainerPath() + "String_Node_Str"+ currentItem.getName(),null);
    getWindowControl().setError(translator.translate("String_Node_Str"));
    return null;
  }
  if (MetaInfoHelper.isLocked(currentItem,ureq)) {
    List<String> lockedFiles=Collections.singletonList(currentItem.getName());
    String msg=MetaInfoHelper.renderLockedMessageAsHtml(translator,folderComponent.getCurrentContainer(),lockedFiles);
    List<String> buttonLabels=Collections.singletonList(translator.translate("String_Node_Str"));
    lockedFiledCtr=activateGenericDialog(ureq,translator.translate("String_Node_Str"),msg,buttonLabels,lockedFiledCtr);
    return null;
  }
  String relFilePath="String_Node_Str" + currentItem.getName();
  if (!folderComponent.getCurrentContainerPath().equals("String_Node_Str")) {
    relFilePath=folderComponent.getCurrentContainerPath() + relFilePath;
  }
  VFSContainer writableRootContainer=folderComponent.getRootContainer();
  ContainerAndFile result=VFSManager.findWritableRootFolderFor(writableRootContainer,relFilePath);
  if (result != null) {
    writableRootContainer=result.getContainer();
    relFilePath=currentItem.getName();
  }
 else {
    relFilePath=currentItem.getName();
    writableRootContainer=folderComponent.getCurrentContainer();
  }
  if (relFilePath.endsWith("String_Node_Str") || relFilePath.endsWith("String_Node_Str")) {
    CustomLinkTreeModel customLinkTreeModel=folderComponent.getCustomLinkTreeModel();
    if (customLinkTreeModel != null) {
      editorc=WysiwygFactory.createWysiwygControllerWithInternalLink(ureq,getWindowControl(),writableRootContainer,relFilePath,true,customLinkTreeModel);
      ((HTMLEditorController)editorc).setNewFile(false);
    }
 else {
      editorc=WysiwygFactory.createWysiwygController(ureq,getWindowControl(),writableRootContainer,relFilePath,true);
      ((HTMLEditorController)editorc).setNewFile(false);
    }
  }
 else {
    editorc=new PlainTextEditorController(ureq,getWindowControl(),(VFSLeaf)currentItem,"String_Node_Str",true,false,null);
  }
  listenTo(editorc);
  putInitialPanel(editorc.getInitialComponent());
  return this;
}