Fixed error handling in createDirecctory (#311)

The error handling in `createDirecctory` had three major issues:

* Racy check for existence of a directory - the directory could've been
  created or deleted in the meantime.
* Attempt to handle race outside the reduce function wouldn't let it
  continue creating the remaining directories.
* All errors that were **not** `EEXISTS` or `ENOENT` were silently
  ignored, leading to lot of frustration and hair pulling, because the
  code continued executing and then failed at attempt to open a file.

These problems were fixed by moving `try` into the reduce closure,
ignoring `EEXISTS` only and rethrowing all other errors. The logic
modifying the error message for `ENOENT` was kept.

connect.js

@@ -230,23 +230,22 @@ connect.setSSOParams = (config) => {
 };
 
 connect.createDirectory = (dirname) => {
-  try {
-    const initDir = path.isAbsolute(dirname) ? path.sep : '';
-    dirname.split(path.sep).reduce((parentDir, childDir) => {
-      const curDir = path.resolve(parentDir, childDir);
-      if (!fs.existsSync(curDir)) {
-        fs.mkdirSync(curDir);
+  const initDir = path.isAbsolute(dirname) ? path.sep : '';
+  dirname.split(path.sep).reduce((parentDir, childDir) => {
+    const curDir = path.resolve(parentDir, childDir);
+    try {
+      fs.mkdirSync(curDir);
+    } catch (err) {
+      if (err.code !== 'EEXIST') {
+        if (err.code === 'ENOENT') {
+          throw new Error(`ENOENT: No such file or directory, mkdir '${dirname}'. Ensure that channel backup path separator is '${(platform === 'win32') ? '\\\\' : '/'}'`);
+        } else {
+          throw err;
+        }
       }
-      return curDir;
-    }, initDir);
-  } catch (err) {
-    if (err.code === 'EEXIST') {
-      return dirname;
     }
-    if (err.code === 'ENOENT') {
-      throw new Error(`ENOENT: No such file or directory, mkdir '${dirname}'. Ensure that channel backup path separator is '${(platform === 'win32') ? '\\\\' : '/'}'`);
-    }
-  }
+    return curDir;
+  }, initDir);
 }
 
 connect.readCookie = (cookieFile) => {