PHP PECL Module Path is Empty.

Symptoms

When trying to install a PECL modules you are confronted with the following issue: 

If installing from the WHM interface, you see no paths are defined.

Module Include Path
Path Path not found.

If installing from the command line, you get the following output:

ERROR: The default config file is not a valid config file or is corrupted.

Description 

These symptoms can appear if PECL is unable to get the correct configuration information.

Workaround

If the file /root/.pearrc file exists and is empty, then you will want to remove or rename that file. 

If this did not address your issue, the problem maybe related to another settings. I would recommend looking at the following articles: 

Using the pecl interface in WHM Module Installers results in open_basedir or disable_functions errors

Unable to Install a Module Using PECL