Add some error-handling when adding SSH keyfiles

site-lisp/db-utils.el

@@ -844,9 +844,13 @@ for KEY-FILE; PASSWORD-FN is called on demand.
 
 This function uses ssh-add to add the key to the currently
 running ssh-agent and waits for the process to finish."
+  (let ((key-file (expand-file-name key-file)))
+
+    (unless (file-readable-p key-file)
+      (user-error "SSH key %s does not exist, aborting" key-file))
+
     (with-environment-variables (("SSH_ASKPASS_REQUIRE" "never"))
-    (let* ((key-file (expand-file-name key-file))
-           (proc (make-process :name "ssh-add"
+      (let ((proc (make-process :name "ssh-add"
                                 :buffer nil
                                 :command (list "ssh-add" key-file)
                                 :filter #'(lambda (process output)
@@ -875,7 +879,7 @@ running ssh-agent and waits for the process to finish."
         ;; intermingle with others.  XXX: is there a more standard way to wait for
         ;; a process to finish?
         (while (process-live-p proc)
-        (sit-for 0.2)))))
+          (sit-for 0.2))))))
 
 (defun db/ssh-key-hash-from-filename (key-file)
   "Return the SHA256 hash value of the SSH key located in KEY-FILE.