[docs-infra] Fix display when the default props is undefined (#41114)

Author: oliviertassinari

docs/src/modules/components/ApiPage/table/PropertiesTable.tsx

@@ -177,7 +177,11 @@ export default function PropertiesTable(props: PropertiesTableProps) {
                   }
                 </td>
                 <td className="default-column">
-                  <span className="MuiApi-table-item-default">{propDefault}</span>
+                  {propDefault ? (
+                    <span className="MuiApi-table-item-default">{propDefault}</span>
+                  ) : (
+                    '-'
+                  )}
                 </td>
                 <td className="MuiPropTable-description-column">
                   {description && <PropDescription description={description} />}