src/utils/combineReducers.js
function getErrorMessage(key, action) {
  var actionType = action && action.type;
  var actionName = actionType && `"${actionType.toString()}"` || 'an action';

  return (
    `Reducer "${key}" returned undefined handling ${actionName}. ` +
    `To ignore an action, you must explicitly return the previous state.`
  );
}
function getErrorMessage(key, action) {
  var actionType = action && action.type;
  var actionName = actionType && `"${actionType.toString()}"` || 'an action';

  return (
    `Reducer "${key}" returned undefined handling ${actionName}. ` +
    `To ignore an action, you must explicitly return the previous state.`
  );
}
function getErrorMessage ( key , action ) { var actionType = action && action . type ; var actionName = actionType && ` ${ actionType . toString ( ) } ` || 'an action' ; return ( ` ${ key } ${ actionName } ` + ` ` ) ; }
/* eslint-disable no-console
/ * eslint - disable no - console