Fix a JS bug in the websocket terminal

app/assets/javascripts/terminal/terminal.js

@@ -6,8 +6,14 @@
     constructor(options) {
       this.options = options || {};
 
-      this.options.cursorBlink = options.cursorBlink || true;
-      this.options.screenKeys = options.screenKeys || true;
+      if (!Object.prototype.hasOwnProperty.call(this.options, 'cursorBlink')) {
+        this.options.cursorBlink = true;
+      }
+
+      if (!Object.prototype.hasOwnProperty.call(this.options, 'screenKeys')) {
+        this.options.screenKeys = true;
+      }
+
       this.container = document.querySelector(options.selector);
 
       this.setSocketUrl();