resources: Register MediaTypes before build

Fixes gohugoio#9971

Author: vanbroup

Diff for: commands/hugo.go

@@ -127,6 +127,12 @@ func initializeConfig(mustHaveConfigFile, failOnInitErr, running bool,
 		return nil, err
 	}
 
+	if h := c.hugoTry(); h != nil {
+		for _, s := range h.Sites {
+			s.RegisterMediaTypes()
+		}
+	}
+
 	return c, nil
 }
 

Diff for: commands/server.go

@@ -272,10 +272,6 @@ func (sc *serverCmd) server(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	for _, s := range c.hugo().Sites {
-		s.RegisterMediaTypes()
-	}
-
 	// Watch runs its own server as part of the routine
 	if sc.serverWatch {