XQuery - Solution for "unbound current node is not supported for XQuery resources"

When below error occurs please check whether the string constant is enclosed with single quate(') such that it can be parsed by the XQyuery compiler

Multiple markers at this line - An error occurred compiling the XQuery resource: The use of an unbound current node is not supported for XQuery resources

Simple XQuery function example with constant and if else condition:

declare function xf:passCurrency(
    $price as xs:string)
    as xs:string {
   
    return if (fn:starts-with($price,"$"))
       then 'Dollar'
       else 'Ruppes'

};