react-redux/es/utils/verifyPlainObject.js

Official React bindings for Redux

import isPlainObject from './isPlainObject';
import warning from './warning';
export default function verifyPlainObject(value, displayName, methodName) {
  if (!isPlainObject(value)) {
    warning(methodName + "() in " + displayName + " must return a plain object. Instead received " + value + ".");
  }
}