fix(input): avoid undefined input help text classname (#1265)

Signed-off-by: David Edler <[email protected]>

Author: edlerd

src/components/Input/Input.test.tsx

@@ -114,8 +114,11 @@ describe("Input", () => {
 
   it("can display help for a checkbox", async () => {
     const help = "Save me!";
-    render(<Input help={help} type="checkbox" />);
+    const { container } = render(<Input help={help} type="checkbox" />);
     expect(screen.getByRole("checkbox")).toHaveAccessibleDescription(help);
+    expect(container.querySelector(".p-form-help-text")).not.toHaveClass(
+      "undefined",
+    );
   });
 
   it("can add additional classes", () => {

src/components/Input/Input.tsx

@@ -32,7 +32,7 @@ export type Props = PropsWithSpread<
     /**
      * Optional class(es) to pass to the help text element.
      */
-    helpClassName?: ReactNode;
+    helpClassName?: string;
     /**
      * The id of the input.
      */
@@ -160,7 +160,7 @@ const Input = ({
       error={error}
       forId={inputId}
       help={help}
-      helpClassName={helpClassName + ""}
+      helpClassName={helpClassName}
       helpId={helpId}
       isTickElement={type === "checkbox" || type === "radio"}
       label={fieldLabel}