Sanity check destinations

config/config.go

@@ -175,6 +175,17 @@ func (c *Config) UpdateFromJSON(j []byte) error {
 		}
 	}
 
+	// check destinations
+	for _, dest := range newConfig.Destinations {
+		s, err := os.Stat(dest.Path)
+		if err != nil {
+			return fmt.Errorf("destination '%s' (%s) is bad: %s", dest.Name, dest.Path, err)
+		}
+		if !s.IsDir() {
+			return fmt.Errorf("destination '%s' (%s) is not a directory", dest.Name, dest.Path)
+		}
+	}
+
 	*c = newConfig
 	return nil
 }

web/config.html

@@ -114,8 +114,9 @@
             <form class="pure-form gropple-config">
                 <fieldset>
                     <legend>Destinations</legend>
-                    <p>You can specify custom destinations here. You can specify that
+                    <p>You can specify custom destinations (directories) here. Downloads can be
-                        downloads be moved to one of these directories after complete.</p>
+                        moved to one of these directories after completion from the index page, 
+                        if you do not want them to be left in the download path above.</p>
                     </p>
                     <template x-for="(dest, i) in config.destinations">
                     <div>
@@ -137,7 +138,7 @@
                     </div>
                 </template>
 
-                <button class="pure-button button-add" href="#" @click.prevent="config.destinations.push({name: 'new destination', path: '/'});">add destination</button>
+                <button class="pure-button button-add" href="#" @click.prevent="config.destinations.push({name: 'new destination', path: '/tmp'});">add destination</button>
 
             </fieldset>
         </form>