Workflow builder error for Custom Action (Error: Send Expects Scriptable Object)

[#1]

I added the JSL below as Custom Action in the Workflow builder. 

The error happened at the For loop (Error: Send Expects Scriptable Object).

While running this script in Script window, it works properly to rename columns header that contain "%, ".

Any idea on how to solve this to make the workflow more smooth? else, need to stop at this step to run Column Renaming script outside the WorkFlow Builder. 

dt = Current Data Table();
searchWords = "%, ";
columnName = dt << Get Column Names;
N = N Items( columnName );

For(j=1, j<= N, j++,
	x = contains(columnName[j], searchWords);
	name = Substr(columnName[j] << Get Name(), x+3);
	If(x  > 0,
		columnName[j] << Set Name(Left(name, Length(name)-1));
	);
);

[#2]

You could ask Get Column Names with the Option "String".
Then you don't need to ask again for the column name:

dt = Current Data Table();
searchWords = "%, ";
columnName = dt << Get Column Names("String");
N = N Items( columnName );

For(j=1, j<= N, j++,
	x = contains(columnName[j], searchWords);
	If(x  > 0,
		name = Substr(columnName[j], x+3);
		Column(columnName[j]) << Set Name(Left(name, Length(name)-1));
	);
);  

[#3]

PS: don't use variable names from this list:
{name, age, sex, height, weight}

[#4]

Add-on (slightly related) question:

Why does calling a list entry alter the list entry?

Running the first part of 

dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
searchWords = "%, ";
:sex << set name ("test%, SEX#");
columnName = dt << Get Column Names;
show(columnName);
columnName[1] << Get Name();
columnName[2] << Get Name();
columnName[3] << Get Name();
columnName[4] << Get Name();
columnName[5] << Get Name();
show(columnName);

N = N Items( columnName );
For(j=1, j<= N, j++,
	x = contains(columnName[j], searchWords);
	myName = Substr(columnName[j] << Get Name(), x+3);
	If(x  > 0,
		columnName[j] << Set Name(Left(myName, Length(myName)-1));
	);
);

adds colons in front of the column names:

and then the for loop runs as expected *)  

*) hm a bit surprising that it works - esp.

contains(columnName[j], searchWords);

[#5]

Hi hogi

Thanks for the tip. 

I added your code into the Workflow Builder step. It was executed without error code, but nothing has changed in the data table. 

Noted that both of our code (with&without "String") work properly when running with Script window, but somehow it does not work in the WorkFlow Builder. 

I figure out that we need to use this instead. 

Column(dt, columnName[j])

Here is the code that works with Workflow Builder. 

searchWords = ", ";
columnName = dt << Get Column Names("String");
N = N Items( columnName );

For(j=1, j<= N, j++,
	x = contains(columnName[j], searchWords);
	colName = Substr(columnName[j], x+length(searchWords));
	If(x  > 0,
		Column(dt, columnName[j]) << Set Name(Left(colName, Length(colName)-1));
	);
);

[#6]

Hi hogi

Thanks for the tip. 

I added your code into the Workflow Builder step. It was executed without error code, but nothing has changed in the data table. 

Noted that both of our code (with&without "String") work properly when running with Script window, but somehow it does not work in the WorkFlow Builder. 

I figure out that we need to use this instead. 

Column(dt, columnName[j])

Here is the code that works with Workflow Builder. 

searchWords = ", ";
columnName = dt << Get Column Names("String");
N = N Items( columnName );

For(j=1, j<= N, j++,
	x = contains(columnName[j], searchWords);
	colName = Substr(columnName[j], x+length(searchWords));
	If(x  > 0,
		Column(dt, columnName[j]) << Set Name(Left(colName, Length(colName)-1));
	);
);

[#7]

Use

dt << get column reference(cols);

to get stable column references.

I just found it in Session 6: Data Tables from JSL Scripters Club Webinars.

(highly recommended!!)

Names Default to Here(1);
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );

cols= dt << get column names();
colRefs = dt << get column reference(cols);
// {Column( "name" ), Column( "age" ), Column( "sex" ), Column( "height" ),Column( "weight" )}

// load another table
Open( "$SAMPLE_DATA/Big Class Families.jmp" );	

//Column(cols[1]) << get name // doesn't work
colRefs[1] << get name; // still works