Explain error when theme activation fails

[joemaller]

As an example, this error: "Error: The 'ex-thm' theme could not be found." could be followed up by a note that renaming the theme folder, or specifying the current theme folder in config.yml would enable automated theme activation.

Raw error:

fatal: [default]: FAILED! =>
var foo = {
  changed: true,
  cmd: "wp theme activate ex-thm",
  delta: "0:00:01.898448",
  end: "2017-05-02 17:49:17.650584",
  failed: true,
  rc: 1,
  start: "2017-05-02 17:49:15.752136",
  stderr: "Debug (bootstrap): Using default global config: /home/vagrant/.wp-cli/config.yml (0.009s)\nDebug (bootstrap): No project config found (0.009s)\nDebug (bootstrap): No package autoload found to load. (0.131s)\nDebug (bootstrap): ABSPATH defined: /vagrant/site/ (0.131s)\nDebug (bootstrap): Begin WordPress load (0.134s)\nDebug (bootstrap): wp-config.php path: /vagrant/site/wp-config.php (0.134s)\nDebug (bootstrap): Loaded WordPress (1.745s)\nDebug (bootstrap): Running command: theme activate (1.746s)\nError: The 'ex-thm' theme could not be found.",
  stderr_lines: [
    "Debug (bootstrap): Using default global config: /home/vagrant/.wp-cli/config.yml (0.009s)",
    "Debug (bootstrap): No project config found (0.009s)",
    "Debug (bootstrap): No package autoload found to load. (0.131s)",
    "Debug (bootstrap): ABSPATH defined: /vagrant/site/ (0.131s)",
    "Debug (bootstrap): Begin WordPress load (0.134s)",
    "Debug (bootstrap): wp-config.php path: /vagrant/site/wp-config.php (0.134s)",
    "Debug (bootstrap): Loaded WordPress (1.745s)",
    "Debug (bootstrap): Running command: theme activate (1.746s)",
    "Error: The 'ex-thm' theme could not be found."
  ],
  stdout: "",
  stdout_lines: []
};