Need to bind intval this to callback within promise.

lib/intval/index.js

@@ -454,7 +454,7 @@ class Intval {
                     this._storeState();
                     return resolve();
                 };
-            });
+            }.bind(this));
         }
         else {
             return new Promise(function (resolve, reject) {
@@ -463,7 +463,7 @@ class Intval {
                     this._storeState();
                     return resolve();
                 };
-            });
+            }.bind(this));
         }
     }
     /**

src/intval/index.ts

@@ -532,7 +532,7 @@ export default class Intval {
 					this._storeState()
 					return resolve()
 				}
-			})
+			}.bind(this))
 		} else {
 			return new Promise (function (resolve, reject) {
 				this._state.frame.cb = (len : number) => {
@@ -540,7 +540,7 @@ export default class Intval {
 					this._storeState()
 					return resolve()
 				}
-			})
+			}.bind(this))
 		}
 	}