fix custom field value equal to 0 ignored

src/components/FeatureType/FeatureTypeCustomForm.vue

@@ -312,7 +312,7 @@ export default {
 
     fillCustomFormData(customFormData) {
       for (const el in customFormData) {
-        if (el && this.form[el] && customFormData[el]) {
+        if (el && this.form[el] && customFormData[el] !== undefined && customFormData[el] !== null) {
           //* check if is an object, because data from api is a string, while import from django is an object
           this.form[el].value = customFormData[el].value
             ? customFormData[el].value