Feature request: common Error enum for read/write

[ngeor]

This can be useful for code that uses both xml::reader::Error and xml::writer::Error (e.g. a function that processes an input XML file and outputs a different XML file). In that case, the code needs to handle two different error structures. The workaround is relatively easy, I can write my own error enum that wraps both read/write errors, together with the From trait implementations. This way, my code can use the ? operator on both xml::reader and xml::writer code.

Maybe this should be provided out of the box by the xml-rs library? Otherwise everyone who is writing an xml transformation function will have to re-invent it.

#[derive(Debug)]
pub enum XmlError {
    ReadError(xml::reader::Error),
    WriterError(xml::writer::Error)
}

impl From<xml::reader::Error> for XmlError {
    fn from(value: xml::reader::Error) -> Self {
        Self::ReadError(value)
    }
}

impl From<xml::writer::Error> for XmlError {
    fn from(value: xml::writer::Error) -> Self {
        Self::WriterError(value)
    }
}