fix: ensure empty DEBUG envvar is ignored

Also ensures the envvar is removed if it's empty, and doesn't permeate
an empty DEBUG when executing doom/reload.

Amend: 8c7711920e
Close: #8310
Co-authored-by: AjaiKN <AjaiKN@users.noreply.github.com>

early-init.el

@@ -49,9 +49,12 @@
 
   ;; UX: Respect DEBUG envvar as an alternative to --debug-init, and to make
   ;;   startup more verbose sooner.
-  (when (getenv-internal "DEBUG")
-    (setq init-file-debug t
-          debug-on-error t))
+  (let ((debug (getenv-internal "DEBUG")))
+    (when (stringp debug)
+      (if (string-empty-p debug)
+          (setenv "DEBUG" nil)
+        (setq init-file-debug t
+              debug-on-error t))))
 
   (let (;; FIX: Unset `command-line-args' in noninteractive sessions, to
         ;;   ensure upstream switches aren't misinterpreted.

lisp/doom-lib.el

@@ -41,7 +41,7 @@ TYPE should be a keyword of any of the known doom-*-error errors (e.g. :font,
 (defvar doom-log-level
   (if init-file-debug
       (if-let* ((level (getenv-internal "DEBUG"))
-                (level (string-to-number level))
+                (level (if (string-empty-p level) 1 (string-to-number level)))
                 ((not (zerop level))))
           level
         2)

lisp/lib/config.el

@@ -45,7 +45,7 @@
           ("EMACSDIR" doom-emacs-dir)
           ("DOOMDIR" doom-user-dir)
           ("DOOMLOCALDIR" doom-local-dir)
-          ("DEBUG" (if doom-debug-mode (number-to-string doom-log-level) "")))
+          ("DEBUG" (if doom-debug-mode (number-to-string doom-log-level))))
        (with-current-buffer
            (compile (format ,command (expand-file-name doom-bin doom-bin-dir)) t)
          (let ((w (get-buffer-window (current-buffer))))