Add guard clauses for file existence and initialize variables

nob.el

@@ -5,7 +5,7 @@
 ;; Author: Robert Rose <overclucker@gmail.com>
 ;; Keywords: lisp eww novel bookmark
 ;; Version: 0.0.1
-;; Package-Requires ((dash "2.15.0) (emacs "24") (ivy "20190214.1032")
+;; Package-Requires ((dash "2.15.0") (emacs "24") (ivy "20190214.1032"))
 
 ;; This program is free software; you can redistribute it and/or modify
 ;; it under the terms of the GNU General Public License as published by
@@ -25,9 +25,9 @@
 ;; This package provides functions for saving and selecting novels for
 ;; for reading in eww. I wrote nob because bookmarking a chapter in eww
 ;; and then always having to remove old bookmarks is ridiculous. nov-save
-;; works by queryinh the bookmark list a pattern that matches the current
+;; works by querying the bookmark list a pattern that matches the current
 ;; url. If it finds a match, it updates the title and url and moves it to
-;; the front of the list. This makes shoosing what to to read next, and
+;; the front of the list. This makes choosing what to read next, and
 ;; picking up where you left off much easier. The nob-select function
 ;; provides an easy to navigate pop up list.
 
@@ -44,6 +44,7 @@
 
 (defcustom nob-bookmarks-file (concat user-emacs-directory "nob-bookmarks.el")
   "Location of the file nob uses for bookmark storage."
+  :type 'file
   :group 'nob)
 
 (defcustom nob-autosave-on-render t
@@ -54,9 +55,11 @@
 (defmacro with-nob (&rest body)
   "Execute body with variable: `novels' set."
   `(let ((novels
-	  (with-temp-buffer
-	    (insert-file-contents nob-bookmarks-file)
-	    (read (buffer-string)))))
+          (if (file-exists-p nob-bookmarks-file)
+              (with-temp-buffer
+                (insert-file-contents nob-bookmarks-file)
+                (read (buffer-string)))
+            '())))
      (unwind-protect ,@body)))
 
 (defmacro with-eww-buffer (&rest body)
@@ -68,7 +71,7 @@
 ;;; I will need to explore options for replacing `--map-first'
 ;;; Maybe it's as simple as popping and pushing. That would be nice.
 (defun nob-update-bookmark (novels title url)
-  "Update an existing bookmark. Returns updated novels list.'
+  "Update an existing bookmark. Returns updated novels list.
 This function has no side affects."
   (--map-first (string-match (car it) url) `(,(car it) ,title ,url)
 	       (--sort (string-match (car it) url) novels)))
@@ -84,17 +87,19 @@ This function has no side affects."
 (cons pattern (cons title url))
 As I've started hacking away at nob mode, I've come
 to realize that I can't simply rewrite the functions.
-I'll need some scafolding in place so that nob remains
+I'll need some scaffolding in place so that nob remains
 functional while I continue working on it."
-  (interactive))
-(with-temp-file (concat user-emacs-directory "nob-bookmarks")
-  (with-nob
-      (let*
-	  ((n (mapcar
-	       (lambda (x)
-		 (cons (car x) (cons (cadr x) (caddr x))))
-	       novels)))
-	(insert (pp n))	)))
+  (interactive)
+  (let ((old-file (concat user-emacs-directory "nob-bookmarks")))
+    (when (file-exists-p old-file)
+      (with-temp-buffer
+        (insert-file-contents old-file)
+        (let ((novels (read (buffer-string)))
+              (n (mapcar
+                   (lambda (x)
+                     (cons (car x) (cons (cadr x) (caddr x))))
+                   novels)))
+          (insert (pp n))))))
 
 (defun nob-save ()
   "Saves current novel."
@@ -112,7 +117,7 @@ functional while I continue working on it."
 		  (progn
 		    (nob-write-file
 		     (push `(,(read-string "Match: " url) ,title ,url) novels))
-		    (message "Bookmarked: %s" title))) )) )) )
+		    (message "Bookmarked: %s" title))) )) ))
 
 (defun nob-select ()
   "Select novel for reading in `eww'."
@@ -125,7 +130,7 @@ functional while I continue working on it."
   (with-nob ; novels: ((pattern title url))
       (let*
 	  ((n (--map (cons (cadr it) (caddr it)) novels))
-	   ;; the mapcar version is bigger.
+	   ;; mapcar version is bigger.
 	   ;; (n (mapcar
 	   ;;     (lambda (x)
 	   ;; 	 (cons (cadr x) (caddr x)))
@@ -140,14 +145,14 @@ functional while I continue working on it."
 	(eww-browse-url s))))
 
 (defun nob-remove ()
-  "Remove an novel."
+  "Remove a novel."
   (interactive)
   (with-nob
       (let ((s (ivy-read "Remove Novel: " (--map (cdr it) novels))))
 	(when (y-or-n-p (format "Remove \"%s\"?" s))
 	  (nob-write-file
 	   (--remove (string-equal s (car (cdr it))) novels))
-	  (message "Removed: %s" s)) )) )
+	  (message "Removed: %s" s)) ))
 
 (defun nob-eww-after-render-hook ()
   "Eww render hook for nob autosave"
@@ -158,7 +163,7 @@ functional while I continue working on it."
 		(let ((n (--first (string-match (car it) url) novels)))
 		  (if n
 		      (if (not (string-equal (nth 2 n) url))
-			  (nob-write-file (nob-update-bookmark novels title url))))) )))) )
+			  (nob-write-file (nob-update-bookmark novels title url))))) ))))
 
 (setq nob-mode-map (make-sparse-keymap))
 (define-key nob-mode-map [?b] 'nob-save)