ArcGIS Enterprise portal and ArcGIS Online: Test execution error. Cannot access property of null object. Verify test data

Error Message

When running an Arcade expression in a Map Viewer pop-up, the following error is returned:

Error:
Test execution error: Execution error - Cannot access property of null object. Verify test data.

Cause

The layers are empty and do not contain any features. The function cannot be executed on an empty dataset. When a layer contains no feature, the attributes are considered missing because there are no values, not even null values.

Solution or Workaround

Add features to the affected layer. Refer to Portal for ArcGIS: Add features or ArcGIS Online: Add features for instructions. The error message can also be addressed by running an in statement within the script to isolate empty attributes. The following is a sample script:

If (IsEmpty(first(fs)) == false){
    Return firstFeature[“Shape_Length”];
}

else{
    return “No value found”;
}