Thumnail placeholder images on Table, Cards and Records view mode for theme.

src/theme-helper/view-mode-cards.vue

@@ -75,6 +75,11 @@ export default {
         items: Array,
         isLoading: false
     },
+    data () {
+        return {
+            thumbPlaceholderPath: tainacan_plugin.base_url + '/admin/images/placeholder_square.png'
+        }
+    },
     methods: {
         goToItemPage(item) {
             window.location.href = item.url;   

src/theme-helper/view-mode-records.vue

@@ -73,7 +73,12 @@ export default {
         collectionId: Number,
         displayedMetadata: Array,
         items: Array,
-        isLoading: false
+        isLoading: false,
+    },
+    data () {
+        return {
+            thumbPlaceholderPath: tainacan_plugin.base_url + '/admin/images/placeholder_square.png'
+        }
     },
     methods: {
         goToItemPage(item) {

src/theme-helper/view-mode-table.vue

@@ -74,7 +74,7 @@
                             <span v-if="column.metadatum == 'row_thumbnail'">
                                 <img 
                                         class="table-thumb" 
-                                        :src="item[column.slug].thumb">
+                                        :src="item[column.slug].thumb ? item[column.slug].thumb : thumbPlaceholderPath">
                             </span> 
                             <p 
                                     v-tooltip="{
@@ -105,6 +105,11 @@ export default {
         items: Array,
         isLoading: false
     },
+    data () {
+        return {
+            thumbPlaceholderPath: tainacan_plugin.base_url + '/admin/images/placeholder_square.png'
+        }
+    },
     methods: {
         goToItemPage(item) {
             window.location.href = item.url;