fix: env output in pm2-describe

ref Unitech#5832

lib/API/UX/pm2-describe.js

@@ -176,7 +176,10 @@ module.exports = function(proc) {
   Object.keys(diff_env).forEach(function(key) {
     var obj = {}
     if (_env[key]) {
-      obj[key] = _env[key].slice(0, process.stdout.columns - 60)
+      // 1. fix env value is not a String and slice is undeinfed
+      // 2. fix process.stdout.columns is undefined and causes empty string output
+      // 3. columns defaults to 300 - same as specified in pm2-ls
+      obj[key] = String(_env[key]).slice(0, (process.stdout.columns || 300) - 60)
       UxHelpers.safe_push(table_env, obj)
     }
   })