I've created a package with a custom action but when I look at the logs after installing the package I see the error

Could not add package actions to the package xml definition, the xml did not parse

with this stack trace

System.Xml.XmlException: There are multiple root elements. Line 1, position 21.\r\n at System.Xml.XmlTextReaderImpl.Throw(Exception e)\r\n at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)\r\n at System.Xml.XmlTextReaderImpl.ParseDocumentContent()\r\n at System.Xml.XmlTextReaderImpl.Read()\r\n at System.Xml.Linq.XElement.ReadElementFrom(XmlReader r, LoadOptions o)\r\n at System.Xml.Linq.XElement.Load(XmlReader reader, LoadOptions options)\r\n at System.Xml.Linq.XElement.Parse(String text, LoadOptions options)\r\n at System.Xml.Linq.XElement.Parse(String text)\r\n at Umbraco.Core.Packaging.PackageDefinitionXmlParser.ToXml(PackageDefinition def) in D:\a\1\s\src\Umbraco.Core\Packaging\PackageDefinitionXmlParser.cs:line 62

The install shows as successfully completed but my custom action was not executed. Below is the package config (with somethings removed for clarity). Any assistance would be great

<?xml version="1.0" encoding="utf-8"?>
<umbPackage>
  <files>
    <!-- I DELETED THE FILES AS IT WAS TOO LONG -->
  </files>
  <info>
    <package>
      <name>Company.Umbraco.Core</name>
      <version>4.0.0</version>
      <iconUrl></iconUrl>
      <license url="http://opensource.org/licenses/MIT">MIT License</license>
      <url>https://company.com/umbraco/packages/core</url>;
      <requirements type="Strict">
        <major>8</major>
        <minor>5</minor>
        <patch>4</patch>
      </requirements>
    </package>
    <author>
      <name>Company</name>
      <website>https://company.com</website>;
    </author>
    <contributors>
      <contributor>WR</contributor>
    </contributors>
    <readme><![CDATA[]]></readme>
  </info>
  <DocumentTypes />
  <Templates />
  <Stylesheets />
  <Macros>
    <!-- I DELETED THE MACROS AS IT WAS TOO LONG -->
  </Macros>
  <DictionaryItems>
   <!-- I DELETED THE DICTIONARY ITEMS AS IT WAS TOO LONG -->
  </DictionaryItems>
  <Languages>
    <Language Id="1" CultureAlias="en-US" FriendlyName="English (United States)" />
  </Languages>
  <DataTypes />
  <Actions>
    <Action runat="install" alias="CustomInstall" />
  </Actions>
</umbPackage>