Upgrade fails if invalid index url

[tomdickman]

It has been noted that if there is no pre-existing Moodle configuration for Elastic Search and the default config values fail to resolve to a response, this will instead return a new \search_elastic\guzzle_exception() which does not contain a getBody() method, thereby breaking the \search_elastic\engine method validate_index()

Here is a stack trace from an upgrade on a Moodle instance:

Default exception handler: Exception - Call to undefined method search_elastic\guzzle_exception::getBody() Debug: Error code: generalexceptionmessage

• line 147 of /search/engine/elastic/classes/engine.php: Error thrown
• line 38 of /search/engine/elastic/db/upgrade.php: call to search_elastic\engine->validate_index()
• line 632 of /lib/upgradelib.php: call to xmldb_search_elastic_upgrade()
• line 1857 of /lib/upgradelib.php: call to upgrade_plugins()
• line 182 of /admin/cli/upgrade.php: call to upgrade_noncore()

[tomdickman]

Closing as fixed by @andrewhancox, thanks for your help!