Read activePlugins from settings & improve error handling

issue #769

- activePlugins were being read from settings in two different ways, this has been simplified
- error handling has been improved so that plugins do not crash Ghost
- used full error messaging capabilities to make it easier to recover from errors

core/ghost.js

@@ -353,34 +353,33 @@ Ghost.prototype.doFilter = function (name, args) {
 
 // Initialise plugins.  Will load from config.activePlugins by default
 Ghost.prototype.initPlugins = function (pluginsToLoad) {
-    pluginsToLoad = pluginsToLoad || JSON.parse(this.settings('activePlugins'));
-
     var self = this;
 
-    // If no activePlugins defined in config settings, look in database settings.
     if (!_.isArray(pluginsToLoad)) {
-        // The value will be resolved in the promise
-        pluginsToLoad = models.Settings.read("activePlugins").then(function (activePluginsSetting) {
-            var settingValue = activePluginsSetting.get('value') || '[]';
 
         try {
             // We have to parse the value because it's a string
-                settingValue = JSON.parse(settingValue) || [];
+            pluginsToLoad = JSON.parse(this.settings('activePlugins')) || [];
         } catch (e) {
-                return when.reject(new Error("Failed to parse activePlugins setting value: " + e.message));
+            errors.logError(
+                'Failed to parse activePlugins setting value: ' + e.message,
+                'Your plugins will not be loaded.',
+                'Check your settings table for typos in the activePlugins value. It should look like: ["plugin-1", "plugin2"] (double quotes required).'
+            );
+            return when.resolve();
+        }
     }
 
-            // Resolve with the array value
-            return when.resolve(settingValue);
-        });
-    }
-
-    return when(pluginsToLoad).then(function (pluginsToLoadValue) {
     return plugins.init(self, pluginsToLoad).then(function (loadedPlugins) {
         // Extend the loadedPlugins onto the available plugins
         _.extend(self.availablePlugins, loadedPlugins);
+    }).otherwise(function (err) {
+        errors.logError(
+            err.message || err,
+            'The plugin will not be loaded',
+            'Check with the plugin creator, or read the plugin documentation for more details on plugin requirements'
+        );
     });
-    }, errors.logAndThrowError);
 };
 
 module.exports = Ghost;

core/server.js

@@ -471,4 +471,4 @@ when(ghost.init()).then(function () {
         }
 
     });
-}, errors.logAndThrowError);
+}).otherwise(errors.logAndThrowError);