Error adding leaflet marker in vue.js – Cannot read properties of null (reading ‘lat’)

I have the following code in Vue.js that retrieves some information from the database as it gets close to the coordinate. However, my code shows some errors when adding the markers to the leaflet map (getContributionsAndEMSI function), as shown in the following image. Also, sometimes the map indicates that the instance has already been initialized, even though I try to handle this situation within the beforeMount hook.

Vue.js code:

<template>
  <div id="map-container" class="w-full h-full z-10"></div>
</template>

<script>
/* eslint-disable global-require */
/* eslint-disable no-underscore-dangle */

import 'leaflet/dist/leaflet.css';

import L from 'leaflet';

import shp from 'shpjs';

import _ from 'lodash';

import wkt from 'wkt';
import EMSI from '../services/EMSI';
import Shapefile from '../services/Shapefile';
import contribution from '../services/Contribution';

import genHexColor from '../utils/colorGenerator';

delete L.Icon.Default.prototype._getIconUrl;

L.Icon.Default.mergeOptions({
  iconRetinaUrl: require('leaflet/dist/images/marker-icon-2x.png'),
  iconUrl: require('leaflet/dist/images/marker-icon.png'),
  shadowUrl: require('leaflet/dist/images/marker-shadow.png'),
});

export default {
  props: {
    useUserLocation: {
      type: Boolean,
      default: false,
    },
  },
  data() {
    return {
      map: null,

      contributions: [],
      emsis: [],
    };
  },
  methods: {
    async getUserLocation() {
      try {
        const geolocation = await new Promise((resolve, reject) => {
          navigator.geolocation.getCurrentPosition(resolve, reject);
        });

        this.coords = geolocation.coords;
      } catch (error) {
        this.coords = { latitude: -20.7542, longitude: -42.8819 };
      }
    },
    getContributionsAndEMSI: _.debounce(async function (x, y) {
      let result = await contribution.index(x, y);
      if (result.success) {
        this.contributions = result.contribution;
      }

      result = await EMSI.index(x, y);
      if (result.success) {
        this.emsis = result.emsi;
      }

      // Error on showing contributions
      this.contributions.forEach((elemento) => {
        if (elemento.local.indexOf('POINT') !== '-1') {
          L.marker(wkt.parse(elemento.local).coordinates).addTo(this.map).bindPopup(
            `${'<strong>Tipo de colaboração: </strong>Colaboração normal<br>'
            + '<strong>Data de ocorrência:</strong> '}${elemento.occurrence}<br>`
            + `<strong>Vítimas:</strong> ${elemento.victims}<br>`
            + `<strong>Risco de danos:</strong> ${elemento.risk_damage}<br>`
            + `<strong>Descrição:</strong> ${elemento.desc}<br>`
            + `<strong>Categoria:</strong> ${elemento.category_name}`,
          );
        } else if (elemento.local.indexOf('LINESTRING') !== '-1') {
          L.polyline(wkt.parse(elemento.local).coordinates).addTo(this.map).bindPopup(
            `${'<strong>Tipo de colaboração: </strong>Colaboração normal<br>'
            + '<strong>Data de ocorrência:</strong> '}${elemento.occurrence}<br>`
            + `<strong>Vítimas:</strong> ${elemento.victims}<br>`
            + `<strong>Risco de danos:</strong> ${elemento.risk_damage}<br>`
            + `<strong>Descrição:</strong> ${elemento.desc}<br>`
            + `<strong>Categoria:</strong> ${elemento.category_name}`,
          );
        } else if (elemento.local.indexOf('POLYGON') !== '-1') {
          L.polygon(wkt.parse(elemento.local).coordinates).addTo(this.map).bindPopup(
            `${'<strong>Tipo de colaboração: </strong>Colaboração normal<br>'
            + '<strong>Data de ocorrência:</strong> '}${elemento.occurrence}<br>`
            + `<strong>Vítimas:</strong> ${elemento.victims}<br>`
            + `<strong>Risco de danos:</strong> ${elemento.risk_damage}<br>`
            + `<strong>Descrição:</strong> ${elemento.desc}<br>`
            + `<strong>Categoria:</strong> ${elemento.category_name}`,
          );
        }
      });

      // FIM - Visualização das contribuições
    }, 2000), // Espera 2 segundos pra mandar a requisição
    async fetchAndShow(e) {
      const center = e.target.getCenter();

      await this.getContributionsAndEMSI(center.lat, center.lng);
    },
  },
  beforeMount() {
    if (this.map) { this.map.off(); this.map.remove(); }
  },
  async mounted() {
    if (this.useUserLocation) {
      await this.getUserLocation();
    } else {
      this.coords = { latitude: -20.7542, longitude: -42.8819 };
    }

    const osm = L.tileLayer('https://{s}.tile.osm.org/{z}/{x}/{y}.png', {
      minZoom: 5,
      attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors',
    });

    const satellite = L.tileLayer.wms(
      'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
      {
        minZoom: 5,
        maxZoom: 17,
        attribution:
          'Tiles &copy; Esri &mdash; Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community',
      },
    );

    const baseMap = {
      'Open Street Map': osm,
      'Visão Satélite': satellite,
    };

    // Definição e plotagem do mapa
    const map = L.map('map-container', {
      center: [this.coords.latitude, this.coords.longitude],
      layers: [osm],
      zoom: 15,
    });

    const layerControl = L.control.layers(baseMap, null, { collapse: true }).addTo(map);

    L.control.scale({ metric: true, imperial: false }).addTo(map);

    const center = map.getCenter();
    await this.getContributionsAndEMSI(center.lat, center.lng);

    map.on('dragend', this.fetchAndShow);

    // INÍCIO - Indexação de Shapefiles
    const shapes = await Shapefile.index('y');
    if (shapes.success) {
      shapes.shapefile.forEach((s) => {
        const randomColor = genHexColor();

        shp(s.uri)
          .then((data) => {
            let shpName = data.fileName.replaceAll(/[-_]/g, ' ');

            if (shpName.length > 25) {
              shpName = `${shpName.slice(0, 26)}...`;
            }

            layerControl.addOverlay(
              L.geoJSON(data, {
                style() {
                  return { color: randomColor };
                },
              }),
              shpName,
            );
          })
          .catch((err) => {
            console.warn('Um ou mais arquivos não possuem layers!', err);
          });
      });
    }
    // FIM - Indexação de Shapefiles

    this.map = map;
  },
};
</script>