chore: changes from review

Signed-off-by: Richard Case <[email protected]>

pkg/provider/registry/registry.go

@@ -19,7 +19,7 @@ func RegisterProvider(name string, factory provider.Factory) error {
 	defer pluginsLock.Unlock()
 
 	if _, exists := plugins[name]; exists {
-		return ErrDuplicatePlugin
+		return fmt.Errorf("plugin %s has already been registered", name)
 	}
 
 	plugins[name] = factory
@@ -37,19 +37,17 @@ func GetPluginInstance(ctx context.Context, name string, runtime *provider.Runti
 		return factoryFunc(ctx, runtime)
 	}
 
-	return nil, fmt.Errorf("getting plugin %s: %w", name, ErrPluginNotFound)
+	return nil, fmt.Errorf("plugin %s not found", name)
 }
 
 // ListPlugins returns a list of the plugin names that have been registered.
 func ListPlugins() []string {
 	pluginsLock.RLock()
 	defer pluginsLock.RUnlock()
 
-	names := make([]string, len(plugins))
-	i := 0
+	names := []string{}
 	for name := range plugins {
-		names[i] = name
-		i++
+		names = append(names, name)
 	}
 
 	return names