fix: wrap error from fast-xml-parser when invalid xml parsed

[WillieRuemmele]

What does this PR do?

when the fast-xml-parser library throws an error due to invalid xml, we will parse that error, and add the file that caused the error.

given a custom labels xml file

<?xml version="1.0" encoding="UTF-8"?>
</CustomLabels xmlns="http://soap.sforce.com/2006/04/metadata">
  <labels>
    <fullName>force_app_Label_1</fullName>
    <language>en_US</language>
    <protected>true</protected>
    <shortDescription>force-app Label 1</shortDescription>
    <value>force-app</value>
  </labels>
</CustomLabels>

note the opening CustomLabels tag is actually a closing tag

What issues does this PR fix or reference?

#1261, @W-10119453@

Functionality Before

TypeError: Cannot read property 'addChild' of undefined

Functionality After

 Component conversion failed: error parsing dreamhouse-lwc/force-app/main/default/labels/CustomLabels.labels-meta.xml due to:
  message: Closing tag 'CustomLabels' can't have attributes or invalid starting..
  line: 2.
  code: InvalidTag.

[mshanemc]

+1

[mshanemc]

I think having them both use a sharedprivate parseAndValidateXML() would be more DRY.

[WillieRuemmele]

I had that for a while - but it was causing testing issues because parse was stubbed, but I got it working 👍

[mshanemc]

QA notes

this was pretty hard to QA (SDR doesn't care about most xml or parse it on a source:convert or deploy, including apexClasses or object/field stuff).

my VSCode had an xml extension that would remove stuff inside a self-closing tag. I finally got the new, improved error to happen via

<?xml version="1.0" encoding="UTF-8"?>
<CustomLabels xmlns="http://soap.sforce.com/2006/04/metadata">
  <labels>
    <fullName>force_app_Label_1</fullName>
    <language>en_US</language>
    <protected>true</protected>
    <shortDescription>force-app Label 1</shortDescription>
    <value>force-app</value>
  </labels>
  <CustomLabels>
    <SelfClos

✅ resulted in

../../plugin-source/bin/run force:source:convert -d force-app --outputdir mdapiOut
ERROR running force:source:convert:  Component conversion failed: error parsing /Users/shane.mclaughlin/eng/repros/mdapiDeployReport/force-app/main/default/labels/CustomLabels.labels-meta.xml due to:
  message: Invalid '[    "CustomLabels",    "CustomLabels",    "SelfClos"]' found.
  line: 1
  code: InvalidXml

which is way better than the original error.

It's still possibly to convert/deploy a lot of invalid xml (well, the metadata API throws the errors back).

🤷🏻‍♂️ It only throws the error on the first failure--you can't get all the xml errors in your project