NullPointerException When Input Field Is Left Empty in ChartRedrawView

[jturfanbasis]

Description

When entering a blank value (null) in any of the input fields (e.g., Instagram, Twitter, Facebook, LinkedIn) and clicking the "Redraw Chart" button, the application throws a java.lang.NullPointerException. The input validation for empty fields is missing.

Additionally, the input fields accept invalid inputs such as only -or + (which are not numbers). Clicking the button causes the application to throw the same exception.

Steps to Reproduce

1. Navigate to the page googlecharts > types > ChartRedrawView.java
2. Delete the value in any input field (e.g., "Value for Instagram") so that it becomes blank.
3. Click the "Redraw Chart" button.
4. Observe the application behavior.

Expected Behavior

The application should validate the input fields and display an appropriate error message when the field is left blank. The application should not throw an exception.