refactor: init UserError, a custom Error object

This will be used for errors that are to be delivered to users, AND not
to be logged into the server (as in it stacktraces and all).
This will eventually remove the need to throw string literals.

In this commit, this has only been implemented on albumsController.js,
but more will soon to come.

controllers/albumsController.js

@@ -7,6 +7,8 @@ const paths = require('./pathsController')
 const perms = require('./permissionController')
 const uploadController = require('./uploadController')
 const utils = require('./utilsController')
+const apiErrorsHandler = require('./handlers/apiErrorsHandler.js')
+const UserError = require('./utils/UserError')
 const config = require('./../config')
 const logger = require('./../logger')
 const db = require('knex')(config.database)
@@ -66,10 +68,11 @@ self.getUniqueRandomName = async () => {
     return identifier
   }
 
-  throw 'Sorry, we could not allocate a unique random identifier. Try again?'
+  throw new UserError('Failed to allocate a unique identifier for the album. Try again?', 500)
 }
 
 self.list = async (req, res, next) => {
+  try {
     const user = await utils.authorize(req, res)
     if (!user) return
 
@@ -87,7 +90,6 @@ self.list = async (req, res, next) => {
       }
     }
 
-  try {
     // Query albums count for pagination
     const count = await db.table('albums')
       .where(filter)
@@ -164,12 +166,12 @@ self.list = async (req, res, next) => {
 
     return res.json({ success: true, albums, count, users, homeDomain })
   } catch (error) {
-    logger.error(error)
-    return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
+    return apiErrorsHandler(error, req, res, next)
   }
 }
 
 self.create = async (req, res, next) => {
+  try {
     const user = await utils.authorize(req, res)
     if (!user) return
 
@@ -179,7 +181,6 @@ self.create = async (req, res, next) => {
 
     if (!name) return res.json({ success: false, description: 'No album name specified.' })
 
-  try {
     const album = await db.table('albums')
       .where({
         name,
@@ -211,8 +212,7 @@ self.create = async (req, res, next) => {
 
     return res.json({ success: true, id: ids[0] })
   } catch (error) {
-    logger.error(error)
-    return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
+    return apiErrorsHandler(error, req, res, next)
   }
 }
 
@@ -222,6 +222,7 @@ self.delete = async (req, res, next) => {
 }
 
 self.disable = async (req, res, next) => {
+  try {
     const user = await utils.authorize(req, res)
     if (!user) return
 
@@ -229,7 +230,6 @@ self.disable = async (req, res, next) => {
     const purge = req.body.purge
     if (!Number.isFinite(id)) return res.json({ success: false, description: 'No album specified.' })
 
-  try {
     if (purge) {
       const files = await db.table('files')
         .where({
@@ -264,17 +264,14 @@ self.disable = async (req, res, next) => {
       .then(row => row.identifier)
 
     await paths.unlink(path.join(paths.zips, `${identifier}.zip`))
-  } catch (error) {
-    if (error && error.code !== 'ENOENT') {
-      logger.error(error)
-      return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
-    }
-  }
-
     return res.json({ success: true })
+  } catch (error) {
+    return apiErrorsHandler(error, req, res, next)
+  }
 }
 
 self.edit = async (req, res, next) => {
+  try {
     const user = await utils.authorize(req, res)
     if (!user) return
 
@@ -300,7 +297,6 @@ self.edit = async (req, res, next) => {
       }
     }
 
-  try {
     const album = await db.table('albums')
       .where(filter)
       .first()
@@ -358,8 +354,7 @@ self.edit = async (req, res, next) => {
       return res.json({ success: true, name })
     }
   } catch (error) {
-    logger.error(error)
-    return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
+    return apiErrorsHandler(error, req, res, next)
   }
 }
 
@@ -370,12 +365,12 @@ self.rename = async (req, res, next) => {
 }
 
 self.get = async (req, res, next) => {
+  try {
     const identifier = req.params.identifier
     if (identifier === undefined) {
       return res.status(401).json({ success: false, description: 'No identifier provided.' })
     }
 
-  try {
     const album = await db.table('albums')
       .where({
         identifier,
@@ -416,12 +411,12 @@ self.get = async (req, res, next) => {
       files
     })
   } catch (error) {
-    logger.error(error)
-    return res.status(500).json({ success: false, description: 'An unexpected error occcured. Try again?' })
+    return apiErrorsHandler(error, req, res, next)
   }
 }
 
 self.generateZip = async (req, res, next) => {
+  try {
     const versionString = parseInt(req.query.v)
 
     const identifier = req.params.identifier
@@ -439,7 +434,6 @@ self.generateZip = async (req, res, next) => {
       })
     }
 
-  try {
     const album = await db.table('albums')
       .where({
         identifier,
@@ -547,8 +541,7 @@ self.generateZip = async (req, res, next) => {
     self.zipEmitters.get(identifier).emit('done', filePath, fileName)
     return res.download(filePath, fileName)
   } catch (error) {
-    logger.error(error)
-    return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
+    return apiErrorsHandler(error, req, res, next)
   }
 }
 
@@ -589,20 +582,21 @@ self.listFiles = async (req, res, next) => {
 }
 
 self.addFiles = async (req, res, next) => {
+  let ids, albumid, failed, albumids
+  try {
     const user = await utils.authorize(req, res)
     if (!user) return
 
-  const ids = req.body.ids
+    ids = req.body.ids
     if (!Array.isArray(ids) || !ids.length) {
       return res.json({ success: false, description: 'No files specified.' })
     }
 
-  let albumid = parseInt(req.body.albumid)
+    albumid = parseInt(req.body.albumid)
     if (isNaN(albumid) || albumid < 0) albumid = null
 
-  let failed = []
-  const albumids = []
-  try {
+    failed = []
+    albumids = []
     if (albumid !== null) {
       const album = await db.table('albums')
         .where('id', albumid)
@@ -646,14 +640,13 @@ self.addFiles = async (req, res, next) => {
 
     return res.json({ success: true, failed })
   } catch (error) {
-    logger.error(error)
-    if (failed.length === ids.length) {
+    if (Array.isArray(failed) && (failed.length === ids.length)) {
       return res.json({
         success: false,
         description: `Could not ${albumid === null ? 'add' : 'remove'} any files ${albumid === null ? 'to' : 'from'} the album.`
       })
     } else {
-      return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
+      return apiErrorsHandler(error, req, res, next)
     }
   }
 }

controllers/handlers/apiErrorsHandler.js

@@ -0,0 +1,30 @@
+const UserError = require('./../utils/UserError')
+const logger = require('./../../logger')
+
+module.exports = (error, req, res, next) => {
+  if (!res) {
+    return logger.error(new Error('Missing "res" object.'))
+  }
+
+  // Intentional error messages to be delivered to users
+  const isUserError = error instanceof UserError
+
+  // ENOENT or missing file errors, typically harmless, so do not log stacktrace
+  const isENOENTError = error instanceof Error && error.code === 'ENOENT'
+
+  if (!isUserError && !isENOENTError) {
+    logger.error(error)
+  }
+
+  const statusCode = isUserError
+    ? error.statusCode
+    : 500
+
+  const description = isUserError
+    ? error.message
+    : 'An unexpected error occurred. Try again?'
+
+  return res
+    .status(statusCode)
+    .json({ success: false, description })
+}

controllers/utils/UserError.js

@@ -0,0 +1,11 @@
+class UserError extends Error {
+  constructor (message, statusCode) {
+    super(message)
+
+    this.statusCode = statusCode !== undefined
+      ? statusCode
+      : 400
+  }
+}
+
+module.exports = UserError