Need to hide column data when it is folder or display data when it is file on SharePoint document li

We are using "Column Formatting" option on SP document library for particular column. When it folder, then that option need to hide, if it file or document inside the folder, then option need to visible. Below json code i am trying but its is hiding option for both file and folder. Can anyone suggest us with correct code line.

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/column-formatting.schema.json",
  "elmType": "button",
  "customRowAction": {
    "action": "executeFlow",
    "actionParams": "{\"id\": \"\"}"
  },
  "attributes": {
    "class": "ms-fontColor-themePrimary ms-fontColor-themeDarker--hover"
  },
  "style": {
    "border": "none",
    "cursor": "pointer",
    "background-color": "#D5D5D5",
    "color": "#000",
    "padding": "4px 4px 4px 10px",
    "border-radius": "5px",
    "display": "=if([$ItemType]=='Folder', 'none', 'inherit')"
  },
  "children": [
    {
      "elmType": "span",
      "txtContent": "Request approval"
    }
  ]
}