| ERROR | [XPTY0004] Expression type does not match a required type |
| CAUSE | It is a type error if, during the static analysis phase, an expression is found to have a static type that is not appropriate for the context in which the expression occurs, or during the dynamic evaluation phase, the dynamic type of a value does not match a required type as specified by the matching rules in 2.5.4 SequenceType Matching. |
| ACTION | Check the expression type. |