whenOrNull<TResult extends Object?>  method 
      
  
TResult?
whenOrNull<TResult extends Object?>( 
    
- TResult? $default(- String abi,
- String method,
- TokensObject params
 
A variant of when that fallback to returning null
It is equivalent to doing:
switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}
Implementation
@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( String abi,  String method,  TokensObject params)?  $default,) {final _that = this;
switch (_that) {
case _FunctionCall() when $default != null:
return $default(_that.abi,_that.method,_that.params);case _:
  return null;
}
}