reverted:
--- b/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
+++ a/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
@@ -78,18 +78,7 @@
    * {@inheritdoc}
    */
   public function isEmpty() {
+    return empty($this->value) && (string) $this->value !== '0';
-    // Based on the PHP empty() function the value is not empty, so there's no need to continue.
-    if (!empty($this->value)) {
-      return FALSE;
-    }
-    // Type of  list_boolean.
-    elseif (isset($this->type) && $this->type == 'list_boolean') {
-      return (string) $this->value === '0';
-    }
-    // Other types.
-    else {
-      return (string) $this->value !== '0';
-    }
   }
 
   /**
only in patch2:
unchanged:
--- a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
@@ -78,7 +78,18 @@ public static function generateSampleValue(FieldDefinitionInterface $field_defin
    * {@inheritdoc}
    */
   public function isEmpty() {
-    return empty($this->value) && (string) $this->value !== '0';
+    // Based on the PHP empty() function the value is not empty, so there's no need to continue.
+    if(!empty($this->value)) {
+      return FALSE;
+    }
+    // Type of list_boolean
+    elseif (isset($this->type) && $this->type == 'list_boolean') {
+      return (string) $this->value === '0';
+    }
+    // Other types.
+    else {
+      return (string) $this->value !== '0';
+    }
   }
 
   /**