Add warning if db adapter package isn't found

Author: mxstbr

src/db.js

@@ -1,10 +1,20 @@
 const flatfile = require('flat-file-db')
 const promise = require('promise')
+const { repeatCharacter } = require('./utils')
 
 let adapter
 
 if (process.env.DB_ADAPTER) {
-  adapter = require('micro-analytics-adapter-' + process.env.DB_ADAPTER)
+  const adapterName = 'micro-analytics-adapter-' + process.env.DB_ADAPTER
+  try {
+    adapter = require(adapterName)
+  } catch (err) {
+    if (err.code === 'MODULE_NOT_FOUND') {
+      // Console.error a warning message, but normally exit the process to avoid printing ugly npm ERR lines and stack trace.
+      console.error(`\n${repeatCharacter(' ', 22)}⚠️ ERROR ⚠️\n${repeatCharacter('-', 55)}\nYou specified "${process.env.DB_ADAPTER}" as the DB_ADAPTER, but no package\ncalled "${adapterName}" was found.\n\nPlease make sure you spelled the name correctly and\nhave "npm install"ed the necessary adapter package!\n${repeatCharacter('-', 55)}\n`)
+      process.exit(0)
+    }
+  }
 } else {
   adapter = require('./flat-file-adapter')
 }

src/utils.js

@@ -24,5 +24,8 @@ const pushView = async (key, view) => {
   }
 }
 
+const repeatCharacter = (char, n) => `${Array(n + 1).join(char)}`
+
 module.exports = exports
 exports.pushView = pushView
+exports.repeatCharacter = repeatCharacter