Improve IPFS finding in example

Author: interfect

README.md

@@ -185,14 +185,9 @@ There's still a bit of work required to start up a node in a robust way (i.e. wi
 
 ```javascript
 // Find the IPFS implementation
-var IPFS
-if (!(typeof require === 'undefined')) {
-  // Can load through Node
-  IPFS = require('ipfs')
-} else if (!(typeof Ipfs === 'undefined')) {
-  // Can load through browser global
-  IPFS = Ipfs
-}
+const IPFS = typeof Ipfs !== 'undefined' ? Ipfs  // browser global
+  : typeof require === 'function' ? require('ipfs') // cjs require
+  : throw new Error('could not load IPFS')
 
 // Make an IPFS node
 var ipfs = new IPFS()