Error found

The actual return type does not match the sequence type declared in the function's signature: lex:get-subleg(xs:string) element(). Expected cardinality: exactly one, got 0.

XQuery Stack Trace
lex:get-subleg(xs:string)16:13
Java Stack Trace:
Class NameMethod NameFile NameLine
org.exist.xquery.DynamicCardinalityCheckevalDynamicCardinalityCheck.java80
org.exist.xquery.DynamicTypeCheckevalDynamicTypeCheck.java61
org.exist.xquery.FunctionCallevalFunctionFunctionCall.java274
org.exist.xquery.FunctionCallevalFunctionCall.java201
org.exist.xquery.AbstractExpressionevalAbstractExpression.java61
org.exist.xquery.PathExprevalPathExpr.java241
org.exist.xquery.LetExprevalLetExpr.java155
org.exist.xquery.LetExprevalLetExpr.java206
org.exist.xquery.LetExprevalLetExpr.java206
org.exist.xquery.LetExprevalLetExpr.java206
org.exist.xquery.BindingExpressionevalBindingExpression.java158
org.exist.xquery.AbstractExpressionevalAbstractExpression.java61
org.exist.xquery.PathExprevalPathExpr.java241
org.exist.xquery.AbstractExpressionevalAbstractExpression.java61
org.exist.xquery.XQueryexecuteXQuery.java228
org.exist.xquery.XQueryexecuteXQuery.java183
org.exist.xmldb.LocalXPathQueryServiceexecuteLocalXPathQueryService.java185
org.exist.http.servlets.XQueryServletprocessXQueryServlet.java414
org.exist.http.servlets.XQueryServletdoGetXQueryServlet.java171
javax.servlet.http.HttpServletserviceHttpServlet.java743