* Add test for #4752: Nil pointer dereference in waitForPluginLoad
This test demonstrates the bug where waitForPluginLoad() panics with a nil
pointer dereference when a plugin fails during startup before the reattach
config is set.
The test creates a runningPlugin with reattach=nil and closes the failed
channel, simulating a plugin that fails in startPluginProcess before
initializePlugin is called.
* Fix#4752: Add nil check for reattach in waitForPluginLoad
Adds a nil pointer check before accessing p.reattach.Pid when a plugin
fails during startup. If the plugin fails before the reattach config is
set (e.g., in startPluginProcess), reattach will be nil and the code
would previously panic when trying to log the PID.
The fix checks if reattach is nil and logs an appropriate message in
each case, preventing the panic while still providing useful debugging
information.
