What is the cause of the InputDataNotFoundException and what can I do about it?

Question

I created a script, but the following error occurred.
What is the cause of the error and what can I do about it?

com.appresso.ds.common.dp.InputDataNotFoundException

Answer

The error occurs when input data is not linked.

-Causes and solutions

1. Data flow or process flow is not drawn.
   [Cause]
   The error may be caused by the fact that the input data flow or process flow is not connected to the component where the event occurs.
   
   [Solution]
   Please check if the error can be resolved by connecting data flow or process flow to the component.
   
   
2. Script is in an invalid state.
   [Cause]
   Other than above, there is a possibility that the internal Mapper data placed in front of the component where the error occurs is in an invalid state, and the input data is not linked, resulting in the output of the corresponding error.
   
   [Solution]
   Please check if the error is resolved by deleting the data flow and re-drawing it.