chore: Fix TS & update ci

Author: zombieJ

.travis.yml

@@ -14,4 +14,5 @@ script:
 env:
   matrix:
   - TEST_TYPE=lint
-  - TEST_TYPE=test
+  - TEST_TYPE=test
+  - TEST_TYPE=compile

src/Popup.tsx

@@ -94,6 +94,7 @@ class Popup extends Component<PopupProps, PopupState> {
     targetHeight: undefined,
 
     status: null,
+    prevVisible: null, // eslint-disable-line react/no-unused-state
     alignClassName: null,
   };