After splitting a string the length of the result is Cannot read property "length" from null (vRO 7)

I am trying to parse a string by using split. Unfortunately, Orchestrator complains that "Cannot read property "length" from null".

My code:

System.log( "inputExecArgs = " + inputExecArgs );
Server.log( "inputExecArgs = " + inputExecArgs );
System.log( "Object.prototype.toString.call( inputExecArgs ) = " + Object.prototype.toString.call( inputExecArgs ) );
Server.log( "Object.prototype.toString.call( inputExecArgs ) = " + Object.prototype.toString.call( inputExecArgs ) );
var inputTokens = inputExecArgs.split( "{" );
System.log( "inputTokens = " + inputTokens );
Server.log( "inputTokens = " + inputTokens );
if ( inputTokens = null ){
 System.log( "inputTokens is null" );
 Server.log( "inputTokens is null" );
}else{
 System.log( "inputTokens not null" );
 Server.log( "inputTokens not null" );
 System.log( "Object.prototype.toString.call( inputTokens ) = " + Object.prototype.toString.call( inputTokens ) );
 Server.log( "Object.prototype.toString.call( inputTokens ) = " + Object.prototype.toString.call( inputTokens ) );
 System.log( "----- begin iterating through inputTokens -----" );
 Server.log( "----- begin iterating through inputTokens -----" );
 for (var key in inputTokens) {     //if (tokens.hasOwnProperty(key)) {   System.log( key + " -> " + inputTokens[key] );   Server.log( key + " -> " + inputTokens[key] );     //}
 }
 System.log( "----- end iterating through inputTokens -----" );
 Server.log( "----- end iterating through inputTokens -----" );
 var tokensLength = tokens.length
 System.log( "tokensLength = " + tokensLength );
 Server.log( "tokensLength = " + tokensLength );
}

My result:

[2017-11-17 13:50:28.864] [I] *******************************************************************************
[2017-11-17 13:50:28.868] [I] Start: Root workflow name         = Andrew.Parse_input_properties
[2017-11-17 13:50:28.872] [I] Start: Root workflow id           = d5f4738e-e947-45d2-a123-cc62696c1a31
[2017-11-17 13:50:28.876] [I] Start: Current workflow name      = Andrew.Parse_input_properties
[2017-11-17 13:50:28.880] [I] Start: Current workflow id        = d5f4738e-e947-45d2-a123-cc62696c1a31
[2017-11-17 13:50:28.886] [I] Start: Current workflow startDate = 2017-11-17 20:50:27
[2017-11-17 13:50:28.891] [I] *******************************************************************************
[2017-11-17 13:50:28.907] [I] --------------------------------------------------------------------------------
[2017-11-17 13:50:28.911] [I] Start: parse string for curly bracket properties
[2017-11-17 13:50:28.920] [I]
[2017-11-17 13:50:28.924] [I] inputExecArgs =  } {token1} {token2} {
[2017-11-17 13:50:28.927] [I] Object.prototype.toString.call( inputExecArgs ) = [object String]
[2017-11-17 13:50:28.932] [I] inputTokens =  } ,token1} ,token2} ,
[2017-11-17 13:50:28.936] [I] inputTokens not null
[2017-11-17 13:50:28.940] [I] Object.prototype.toString.call( inputTokens ) = [object Main]
[2017-11-17 13:50:28.944] [I] ----- begin iterating through inputTokens -----
[2017-11-17 13:50:28.947] [I] ----- end iterating through inputTokens -----
[2017-11-17 13:50:28.953] [E] Error in (Workflow:Andrew.Parse_input_properties / parse string for curly bracket properties (item1)#37) ReferenceError: "tokens" is not defined.
[2017-11-17 13:50:28.964] [E] Workflow execution stack:
***
item: 'Andrew.Parse_input_properties/item1', state: 'failed', business state: 'null', exception: 'ReferenceError: "tokens" is not defined. (Workflow:Andrew.Parse_input_properties / parse string for curly bracket properties (item1)#37)'
workflow: 'Andrew.Parse_input_properties' (d5f4738e-e947-45d2-a123-cc62696c1a31)
|  'input': name=inputExecArgs type=string value= } {token1} {token2} {
|  'output': name=outputExecArgs type=string value=null
|  'no attributes'
*** End of execution stack.

I need to be able to iterate over the result of the split("{"). I Googled this thing to death. I must be missing something obvious or obscure.