Error message. "Props with type Object/Array must use a factory function to return the default value."

A factory function in props looks like this:

props: {
    exampleDefaultObject: {
        type: Object,
        default() {
            return {}
        }
    },
    exampleDefaultArray: {
        type: Array,
        default() {
            return []
        }
    }
},

or in ES6:

props: {
    exampleDefaultObject: {
        type: Object,
        default: () => ({})
    },
    exampleDefaultArray: {
        type: Array,
        default: () => []
    }
},

(for people who come here looking for an explanation of the error in the question 'props with type object/array must use a factory function to return the default value')

Note that when returning an object in an es6 arrow function, you need the parentheses: () => ({}) instead of () => {}

according to your console warn, i find the error

https://github.com/holiber/sl-vue-tree/blob/master/src/sl-vue-tree.js#L30

try to fix it like this:

multiselectKey: {
  type: [String, Array],
  default: function () {
    return ['ctrlKey', 'metaKey']
  },
  validator: function (value) {
    let allowedKeys = ['ctrlKey', 'metaKey', 'altKey'];
    let multiselectKeys = Array.isArray(value) ? value : [value];
    multiselectKeys = multiselectKeys.filter(keyName => allowedKeys.indexOf(keyName ) !== -1);
    return !!multiselectKeys.length;
  }
},

the component default value must use a factory function to return!

try it and hope it can help you