dev/core#3502 - CiviEventDispatcher - Softer errors for not-ready. More comments.

Civi/Core/CiviEventDispatcher.php

@@ -187,7 +187,18 @@ public function dispatch($eventName, Event $event = NULL) {
           throw new \RuntimeException("The dispatch policy prohibits event \"$eventName\".");
 
         case 'not-ready':
-          throw new \RuntimeException("CiviCRM has not bootstrapped sufficiently to fire event \"$eventName\".");
+          // The system is not ready to run hooks -- eg it has not finished loading the extension main-files.
+          // If you fire a hook at this point, it will not be received by the intended listeners.
+          // In practice, many hooks involve cached data-structures, so a premature hook is liable to have spooky side-effects.
+          // This condition indicates a structural problem and merits a consistent failure-mode.
+          // If you believe some special case merits an exemption, then you could add it to `$bootDispatchPolicy`.
+
+          // An `Exception` would be ideal for preventing new bugs, but it can be too noisy for systems with pre-existing bugs.
+          // throw new \RuntimeException("The event \"$eventName\" attempted to fire before CiviCRM was fully loaded. Skipping.");
+          // Complain to web-user and sysadmin. Log a backtrace. We're pre-boot, so don't use high-level services.
+          error_log("The event \"$eventName\" attempted to fire before CiviCRM was fully loaded. Skipping.\n" . \CRM_Core_Error::formatBacktrace(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS), FALSE));
+          trigger_error("The event \"$eventName\" attempted to fire before CiviCRM was fully loaded. Skipping.", E_USER_WARNING);
+          return $event;
 
         default:
           throw new \RuntimeException("The dispatch policy for \"$eventName\" is unrecognized ($mode).");