Better error msg when Instant Client is missing

lib/oracledb.js

@@ -22,13 +22,49 @@ var oracledbInst;
 var Lob = require('./lob.js').Lob;
 var pool = require('./pool.js');
 var connection = require('./connection.js');
+var path;
+var fs;
+var fileExists;
 
 try {
   oracledbCLib =  require('../build/Release/oracledb');
 } catch (err) {
   if (err.code === 'MODULE_NOT_FOUND') {
     oracledbCLib = require('../build/Debug/oracledb');
   } else {
+    path = require('path');
+    fs = require('fs');
+
+    fileExists = function(fullPathToFile) {
+      try {
+          return fs.statSync(fullPathToFile).isFile();
+      }
+      catch (err) {
+          return false;
+      }
+    };
+
+    process.env.PATH.split(path.delimiter).forEach(function(dir) {
+      var msg = function(){
+        console.log();
+        console.log('**** Found an Oracle client library in PATH in the following directory: ' + dir);
+        console.log('**** But the version is either corrupt or not for the same OS and/or Node.js processor architecture in which you\'re running on.');
+        console.log('**** Your Node.js processor architecture is ' + process.arch + '.');
+        console.log('**** If you have multiple Oracle client directories defined in PATH, only the first one is loaded.');
+        console.log('**** Therefore, the first to appear needs to be correct one.');
+        console.log();
+        throw err;
+      };
+
+      if(fileExists(path.join(dir, 'oci.dll'))) {msg();}
+
+    });
+
+    console.log();
+    console.log('****');
+    console.log('**** AN ORACLE CLIENT LIBRARY WAS NOT FOUND.');
+    console.log('****');
+    console.log();
     throw err;
   }
 }