Fix null error; Fix promise

lib/iwlist.js

@@ -13,6 +13,7 @@ const detector = tool + ' --help';
 
 const macRegex  = /([0-9a-zA-Z]{1}[0-9a-zA-Z]{1}[:]{1}){5}[0-9a-zA-Z]{1}[0-9a-zA-Z]{1}/;
 const cellRegex = /Cell [0-9]{2,} - Address:/;
+const encryptedRegex = /Encryption key:on/g;
 
 /**
  * Parsing the output of iwlist, tool having a lot of different faces :-(
@@ -27,7 +28,8 @@ function parseOutput(str, callback) {
     let blocks = str.split(cellRegex);
 
     blocks.forEach(block => {
-      let network = {};
+      let network = {encrypted: encryptedRegex.test(block)};
+
       let lines   = block.split('\n');
       if (macRegex.exec(lines[0])) {
         // First line is the mac address (always! (?))