Fix error range for cvc-complex-type.2.4.f

[fbricon]

Given this sequence.xsd schema:

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified">
  <xs:element name="root">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="tag"/>
        <xs:element
            name="optional"
            minOccurs="0"
            maxOccurs="2"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

The following xml snippet generates the error: cvc-complex-type.2.4.f: 'optional' can occur a maximum of '2' times in the current sequence. This limit was exceeded. No child element is expected at this point.xml(cvc-complex-type.2.4.f):
`

<?xml version="1.0" encoding="UTF-8" ?>
<root
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="sequence.xsd">
  <tag></tag>
  <optional></optional>
  <optional></optional>
  <optional></optional>
</root>

The diagnostic rang is wrong though, it should cover the last opening tag.