VueJs cannot map (properties of null)

Im using the v-calendar and in the attributes, I want to map through api data. My code is as follows and I used https://vcalendar.io/attributes.html for reference.

  computed: {
    attributes() {
      return [
      {
        key: 'today',
        dates: new Date()
      },
      ...this.$store.getters['resource/list']('actionEvents').map(attr => ({
          dates: attr.dates,
          key: 'range',
          dot: {
            color: attr.color,
          },
          popover: {
            label: attr.description,
          },
          customData: { calendarData : attr },
        })),
      ];
    },

 <popover-row
  v-for="attr in attributes"
  :key="attr.key"
  :attribute="attr">
  {{ attr.customData && attrr.customData.calendarData &&       
  attr.customData.calendarData.description }}
 </popover-row>

I get the following error:

Cannot read properties of null (reading ‘map’)

Does this mean that I’m trying to map something that isn’t an array? Is there a way to rewrite the code so i dont get this error?