Finally fixed error handling. Also added 403 page. And now if something's wrong with DB or your post then your message will be printed to you, so you don't waste your time.

homepage/index.js

@@ -122,11 +122,14 @@ function setRoutes() {
 			if (await guestbook.addPost(post))
 				ctx.redirect("/guestbook");
 		} catch(err) {
-			ctx.type = "text/plain";
+			
-			if (err instanceof MysqlError)
+			if (typeof err == 'object' && err instanceof MysqlError) {
-				ctx.body = `Database failed so your post wasn't added. So your time wasn't wasted here's your message:\n${post.message}`;
+				ctx.response.status = 500;
-			else
+				ctx.response.body = { error: `Database failed so your post wasn't added. Here's your message:`, message: post.message };
-				ctx.body = `Your post was rejected because of "${err}". So your time wasn't wasted here's your message:\n${post.message}`;
+			} else if (typeof err == 'string') {
+				ctx.response.status = 403;
+				ctx.response.body = { error: `Reason why your post was rejected is "${err}". Here's your message:`, message: post.message };
+			}
 		}
 	});
 }
@@ -148,13 +151,15 @@ app
 	.use(async (ctx, next) => {
 		try {
 			await next();
-			if (ctx.status === 404) ctx.throw(404);
+			if (ctx.status !== 200) ctx.throw(ctx.status);
 		} catch (err) {
 			ctx.status = err.status || 500;
 			if (ctx.status === 404)
 				await ctx.render('404');
+			else if (ctx.status === 403)
+				await ctx.render('403', { error: ctx.body });
 			else
-				await ctx.render('500');
+				await ctx.render('500', { error: ctx.body });
 		}
 	})
 	.use(setRoutes().routes())

homepage/views/403.pug

@@ -0,0 +1,34 @@
+extends base.pug
+
+block head
+	style(type="text/css").
+		#error {
+			font-size: 3.5rem;
+			line-height: 5rem;
+			text-align: center;
+			margin: 6rem 0; }
+
+		#error h1 { font-size: 8rem; }
+
+		#description p { text-align: center; }
+
+		#description p:first-child { font-size: 1.4rem; }
+
+block nav
+	nav
+		a(href='/') Home
+		a(href='/stuff') Stuff
+		a(href='/mindflow') Mindflow
+		a(href='/about') About
+		a(href='/guestbook') Guestbook
+		h1 Whoa whoa, watcha tryin'?
+
+block content
+	section#error
+		h1 403
+		| Forbidden
+	
+	if (error)
+		section#description
+			p= error.error
+			p= error.message

homepage/views/500.pug

@@ -10,6 +10,10 @@ block head
 
 		#error h1 { font-size: 8rem; }
 
+		#description p { text-align: center; }
+
+		#description p:first-child { font-size: 1.4rem; }
+
 block nav
 	nav
 		a(href='/') Home
@@ -23,3 +27,8 @@ block content
 	section#error
 		h1 50x
 		| Internal Server Error
+
+	if (error)
+		section#description
+			p= error.error
+			p= error.message