fix(ComboBox): support for legacy field * 6

Author: tenphi

src/components/fields/ComboBox/ComboBox.tsx

@@ -108,7 +108,7 @@ export interface CubeComboBoxProps<T>
     >,
     AriaComboBoxProps<T>,
     AriaTextFieldProps {
-  defaultSelectedKey?: string;
+  defaultSelectedKey?: string | null;
   selectedKey?: string | null;
   onSelectionChange?: (selectedKey: string | null) => void;
   onInputChange?: (inputValue: string) => void;

src/components/fields/TextInputMapper/TextInputMapper.tsx

@@ -347,7 +347,7 @@ function TextInputMapperInput(props: CubeTextInputMapperInputProps) {
         aria-label={placeholder}
         placeholder={placeholder}
         onInputChange={onChange}
-        onSelectionChange={onSelectionChange}
+        onSelectionChange={(val) => onSelectionChange(val ?? '')}
       >
         {(options ?? []).map((option) => (
           <ComboBox.Item key={option}>{option}</ComboBox.Item>