diff --git a/packages/core/src/components/WarningPanel/WarningPanel.tsx b/packages/core/src/components/WarningPanel/WarningPanel.tsx
index e55a3c35f4..3da110c411 100644
--- a/packages/core/src/components/WarningPanel/WarningPanel.tsx
+++ b/packages/core/src/components/WarningPanel/WarningPanel.tsx
@@ -83,8 +83,7 @@ type Props = {
   children?: React.ReactNode;
 };
 
-const capitalize = s => {
-  if (typeof s !== 'string') return '';
+const capitalize = (s: string) => {
   return s.charAt(0).toUpperCase() + s.slice(1);
 };