Installing a legacy pear package in Xubuntu 20.04

Trying to install a legacy pear package on a new version of Ubuntu is a bit of a chore as things are broken. For starters, using

$> sudo apt install php-pear

$> sudo pear install foo

results in errors such as

and

Notice: Trying to access array offset on value of type null in PEAR/Command/Remote.php on line 354
PHP Notice:  Trying to access array offset on value of type null in /usr/share/php/PEAR/Command/Remote.php on line 354

Things to try:

• sudo mkdir -p /tmp/pear/cache
• sudo pear channel-update pear.php.net

  and

  sudo pear list-all -c pear.php.net
• Manually fix the offending statement on line 187 as per the error message:
  sudo vi /usr/share/php/PEAR/REST.php

  This involves checking if the $cacheid variable is null or not.

• Try the pear statements again; it worked for me.
• Install your package: sudo pear install FOO
sudo pear install Numbers_Words-0.18.2