Add simple error handling

Now we don't have to deal with a completely obliterated terminal every time
something breaks! \o/

scripts/sloth.in

@@ -14,6 +14,8 @@
              (config api)
              (config licenses)
              (config parser sexp)
+             (ice-9 exceptions)
+             (sloth common)
              (sloth editor)
              (sloth interface)
              (ncurses curses))
@@ -45,7 +47,14 @@
   "(Listof String) -> Int
 program entrypoint; handle commandline args and call appropriate procedures"
   (define options (getopt-config-auto args %configuration))
-  (start-loop (init-frontend 'ncurses) (option-ref options '(file) #f)))
+  (define frontend (init-frontend 'ncurses))
+  (with-exception-handler
+      (lambda (err)
+        (when (error? err)
+          (end frontend)
+          (format (current-error-port) "An error occurred: ~a" err)))
+    (lambda ()
+      (start-loop frontend (option-ref options '(file) #f)))))
 
 ;;; Local Variables:
 ;;; mode: scheme

sloth/editor.scm

@@ -1,8 +1,9 @@
 (define-module (sloth editor)
+  #:use-module (ice-9 exceptions)
   #:use-module (ice-9 textual-ports)
   #:use-module (oop goops)
-  #:use-module (sloth interface)
   #:use-module (sloth common)
+  #:use-module (sloth interface)
   #:use-module (ts)
   #:export (start-loop))
 

sloth/ncurses.scm

@@ -294,8 +294,9 @@
   (move (get-main-win nc) y-real x-real))
 
 (define-method (end (nc <ncurses-frontend>))
-  (endwin)
-  (quit))
+  (erase (get-main-win nc))
+  (refresh (get-main-win nc))
+  (endwin))
 
 (define-method (write-buffer (nc <ncurses-frontend>) buffer scroll)
   (define win (get-main-win nc))