registerSpellcheck()'s invoke-handler registration guard checked
ipcMain.eventNames(), which only reflects .on()/.once() listeners --
handlers registered via ipcMain.handle() never show up there, so the
guard was a no-op. With closeToTray disabled (or any other path that
lets the main window actually close instead of hide), a second
createWindow() call would hit "Attempted to register a second handler
for 'spellcheck-get-state'", aborting window setup partway through and
leaving a blank window. Use a real module-level flag instead, matching
the pattern already used for this file's .on() listeners.
brenden
eca57c85ef