Fix the bug on Bubble-Picker.

1. Introduction ( What is Bubble-Picker?) 1.1 Bubble-Picker with removing feature : Source => [login to view URL] 1.2 Bubble-Picker: An easy-to-use animation which can be used for content picking for Android Original source = [login to view URL] 2. Bug If you build and run 1.1 Bubble-Picker(with removing feature), then you can see the bugs in android studio. If you fix the bugs, This job is done. 3. More Detail. In JBox2d, [login to view URL]() doesn't work normally. That is to say, I don't know how to remove circle-items from the world in jbox2d. ``` Error Message to fix E/AndroidRuntime: FATAL EXCEPTION: GLThread 2044 Process: [login to view URL], PID: 26298 [login to view URL] at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]$[login to view URL]([login to view URL]) at [login to view URL]$[login to view URL]([login to view URL]) I/Process: Sending signal. PID: 26298 SIG: 9 ``` 4. After fixing the problem, upload the project files or commit to GitHub. I will check it out. 5. Requirements (To pass test cases) In my project, there are data arrays for 6 test cases, you must pass the test cases without errors. -- Must Add/Remove items to BubblePickerAdapter. -- Must use [login to view URL]() to remove items from JBox2d. 6 Required Skills -. Android Studio, -. Kotlin, -. Java, -. OpenGLESv2.0, -. Jbox2d