Fix mode-line in non-file buffers and nil project root crash

- Update the mode-line via window-configuration-change-hook so
  non-file buffers like Magit display correct project info (#1823)
- Use projectile-acquire-root instead of projectile-project-root in
  projectile--run-project-cmd to prevent wrong-type-argument error
  when running commands in newly created projects (#1886)

Author: bbatsov

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bugs fixed
 
+* [#1823](https://github.com/bbatsov/projectile/issues/1823): Update the mode-line via `window-configuration-change-hook` so non-file buffers (e.g. Magit) display the correct project info.
+* [#1886](https://github.com/bbatsov/projectile/issues/1886): Fix `(wrong-type-argument stringp nil)` error when running project commands in a newly created project by using `projectile-acquire-root` instead of `projectile-project-root` in `projectile--run-project-cmd`.
 * [#1748](https://github.com/bbatsov/projectile/issues/1748): Fix `projectile-replace` falling back to the legacy Emacs 25/26 code path on Emacs 27+ because `fileloop` was not loaded.
 * [#1741](https://github.com/bbatsov/projectile/issues/1741): Fix `projectile-replace` treating the search string as a regexp instead of a literal string on Emacs 27+.
 * [#1729](https://github.com/bbatsov/projectile/issues/1729): Fix `projectile-root-top-down` to actually return the topmost matching project root instead of the bottommost.

projectile.el

@@ -569,8 +569,8 @@ Any function that does not take arguments will do."
 
 (defcustom projectile-dynamic-mode-line t
   "If true, update the mode-line dynamically.
-Only file buffers are affected by this, as the update happens via
-`find-file-hook'.
+The mode-line is updated when files are opened via `find-file-hook'
+and when the window configuration changes.
 
 See also `projectile-mode-line-function' and `projectile-update-mode-line'."
   :group 'projectile
@@ -5463,7 +5463,7 @@ If SAVE-BUFFERS is non-nil save all projectile buffers before
 running the command.
 
 The command actually run is returned."
-  (let* ((project-root (projectile-project-root))
+  (let* ((project-root (projectile-acquire-root))
          (default-directory (projectile-compilation-dir))
          (command (projectile-maybe-read-command show-prompt
                                                  command
@@ -6286,6 +6286,14 @@ thing shown in the mode line otherwise."
     (setq projectile--mode-line mode-line))
   (force-mode-line-update))
 
+(defun projectile-update-mode-line-on-window-change ()
+  "Update the mode-line when the window configuration changes.
+This ensures the mode-line is correct in non-file buffers like
+Magit that don't trigger `find-file-hook'."
+  (when projectile-dynamic-mode-line
+    (unless (file-remote-p default-directory)
+      (projectile-update-mode-line))))
+
 (defvar projectile-command-map
   (let ((map (make-sparse-keymap)))
     (define-key map (kbd "4 a") #'projectile-find-other-file-other-window)
@@ -6542,12 +6550,14 @@ Otherwise behave as if called interactively.
     (add-hook 'find-file-hook 'projectile-find-file-hook-function)
     (add-hook 'projectile-find-dir-hook #'projectile-track-known-projects-find-file-hook t)
     (add-hook 'dired-before-readin-hook #'projectile-track-known-projects-find-file-hook t t)
+    (add-hook 'window-configuration-change-hook #'projectile-update-mode-line-on-window-change)
     (advice-add 'compilation-find-file :around #'compilation-find-file-projectile-find-compilation-buffer)
     (advice-add 'delete-file :before #'delete-file-projectile-remove-from-cache))
    (t
     (remove-hook 'project-find-functions #'project-projectile)
     (remove-hook 'find-file-hook #'projectile-find-file-hook-function)
     (remove-hook 'dired-before-readin-hook #'projectile-track-known-projects-find-file-hook t)
+    (remove-hook 'window-configuration-change-hook #'projectile-update-mode-line-on-window-change)
     (advice-remove 'compilation-find-file #'compilation-find-file-projectile-find-compilation-buffer)
     (advice-remove 'delete-file #'delete-file-projectile-remove-from-cache))))