fix(ivy): counsel-rg dying on non-zero exit code

Monkey-patches counsel-rg to ignore non-zero exit codes. This may have
other side effects, but despite it still producing workable resutls, the
command will discard all its results if there are any errors while
scanning a directory.

Ref: abo-abo/swiper#2339
Fix: #3038

modules/completion/ivy/config.el

@@ -211,6 +211,20 @@ results buffer.")
   (when (stringp counsel-rg-base-command)
     (setq counsel-rg-base-command (split-string counsel-rg-base-command)))
 
+  ;; REVIEW: See abo-abo/swiper#2339.
+  (defadvice! +counsel-rg-suppress-error-code-a (fn &rest args)
+    "Ripgrep returns a non-zero exit code if it encounters any trouble (e.g. you
+don't have the needed permissions for a couple files/directories in a project).
+Even if rg continues to produce workable results, that non-zero exit code causes
+counsel-rg to discard the rest of the output to display an error.
+
+This advice suppresses the error code, so you can still operate on whatever
+workable results ripgrep produces, despite the error."
+    :around #'counsel-rg
+    (letf! (defun process-exit-status (code)
+             (funcall process-exit-status (if (= code 2) 0 code)))
+      (apply fn args)))
+
   ;; Integrate with `helpful'
   (setq counsel-describe-function-function #'helpful-callable
         counsel-describe-variable-function #'helpful-variable