Composer "Could not scan for classes" error during update

[sai-mike]

I am receiving this error from Composer:

$  sudo -u www-data php composer.phar update
Could not scan for classes inside "/var/www/mail.<redact>.com/vendor/roundcube/carddav/carddav.php" which does not appear to be a file nor a folder
Could not scan for classes inside "/var/www/mail.<redact>.com/vendor/roundcube/carddav/dbmigrations/" which does not appear to be a file nor a folder
Loading composer repositories with package information
Updating dependencies
Nothing to modify in lock file
Installing dependencies from lock file (including require-dev)
Nothing to install, update or remove
Generating autoload files
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No security vulnerability advisories found.

The directory roundcube/carddav/ does not exist in the vendor directory. I searched the server to delete all of the user composer settings and cleared the composer cache using 'composer clearcache'. I also deleted the lock file and recreated it with an update and then I deleted the vendor folder and ran 'composer install'. None of those fixed the problem.

Next, I searched the vendor folder for 'roundcube/carddav'. This is more complicated because I have the carddav plugin installed and working correctly. I found that string in a file named /var/www/mail.(redact).com/vendor/roundcube/plugin-installer/test-composer/composer.json

The first part of the file contains:

{
"name": "roundcube/plugin-installer-test",
"require": {
"roundcube/carddav": "^4 || ^5"
},

Looking at the .gitignore for the plugin, I see this:

/test-composer/*
!/test-composer/composer.json

So it looks like when I delete the vendor directory and allow composer to re-install it, composer installs /vendor/roundcube/plugin-installer/test-composer/composer.json which it should not. Am I correct and can I just delete this directory to fix the error messages?

Delete