Inside `WP_Community_Events::get_cached_events()`, `WP_Community_Events::get_events_transient_key()` is used to retrieve the transient key name, based on the user's location. However, the transient key can potentially return `false`, resulting in a call to `get_site_transient()` with the `$key` being `false`.
This change first attempts to evaluate and guard against a `false` return from `WP_Community_Events::get_events_transient_key()`. The result is an early `false` return from `WP_Community_Events::get_cached_events()`.
Props malthert, rafiahmedd, audrasjb, costdev.
Fixes#55888.
Built from https://develop.svn.wordpress.org/trunk@54338
git-svn-id: http://core.svn.wordpress.org/trunk@53897 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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