Add guard clauses for file existence and initialize variables

stride.el

@@ -1,5 +1,5 @@
 ;;; Provides Stride minor mode.
-;;; 
+;;;
 (require 'eww)
 (require 'eww-http-code-advice)
 
@@ -9,8 +9,12 @@
 
 (defcustom stride-nav-file (concat user-emacs-directory "stride-nav.el")
   "File that Stride reads site navigation info from."
+  :type 'file
   :group 'stride)
 
+(defvar-local stride-nav '()
+  "Stride navigation list.")
+
 ;; (defcustom stride-nav
 ;;   (with-temp-buffer
 ;;     (insert-file-contents stride-nav-file)
@@ -22,9 +26,10 @@
 (defun stride-read-file ()
   "Read `stride-nav' from `stride-nav-file' file."
   (interactive)
-  (with-temp-buffer
-    (insert-file-contents stride-nav-file)
-    (setq stride-nav (read (buffer-string)))))
+  (when (file-exists-p stride-nav-file)
+    (with-temp-buffer
+      (insert-file-contents stride-nav-file)
+      (setq stride-nav (read (buffer-string)))))
 
 (defun stride-write-file ()
   "Write `stride-nav' to `stride-nav-file' file."
@@ -32,7 +37,7 @@
   (let ((inhibit-message t))
     (with-temp-buffer
       (insert (pp stride-nav))
-      (write-file stride-nav-file))) )
+      (write-file stride-nav-file))))
 
 (defun stride-match ()
   "Return matching stride-nav member."
@@ -67,7 +72,7 @@
   ;;     (eval (nth 1 (stride-match)))))
 
   ;;; Third version. Only gives eww-reload 3 tries.
-  (let ((status (third (plist-get eww-data :error)))
+  (let ((status (third (plist-get eww-data :error))
 	(tries (or (plist-get eww-data :tries) 1)))
     (if (eq status 400)
 	(when (<= tries 3)
@@ -75,13 +80,12 @@
 	  (message "HTTP/1.1 ERROR 400, retry count: %i" (+ tries 1))
 	  (eww-reload))
       (plist-put eww-data :tries 1)
-      (eval (second (stride-match)))))
-  )
+      (eval (second (stride-match))))))
 
 (defun stride-forward ()
   "Goes to next chapter if in view, else advances to next page.
 TODO: move function definition to stride-nav for more flexibility
-when dealing with dificult sites. then eval the lisp here."
+when dealing with difficult sites. then eval the lisp here."
   (interactive)
   (move-to-window-line -1)
   (setq-local bottom (point))
@@ -109,9 +113,10 @@ when dealing with dificult sites. then eval the lisp here."
   (if stride-mode
       (progn
 	(add-hook 'eww-after-render-hook 'stride-eww-after-render-hook nil t)
-	(setq stride-nav (with-temp-buffer
-				 (insert-file-contents stride-nav-file)
-				 (read (buffer-string))))
+	(when (file-exists-p stride-nav-file)
+          (with-temp-buffer
+            (insert-file-contents stride-nav-file)
+            (setq stride-nav (read (buffer-string)))))
 	;; (setq-local stride-mode-on t)
 	;; (stride-update)
 	)