Nevermind my last message. I can guess: lsp-intelephense-stubs isn’t defined until lsp-php is loaded (because that’s where it’s defined), so putting that setq inside (after! lsp-mode ...) is too early to reference it. Therefore:
;;; in $DOOMDIR/config.el
(after! lsp-php
(setq lsp-intelephense-stubs (vconcat lsp-intelephense-stubs ["imagick"])))
However, never time, please include the error message (and a backtrace) when reporting errors.