gvpr incorrectly passes "computed" strings to user-defined functions

Steps to reproduce

copy below to a file named gvprstringBug1.gvpr
run with this command line echo |/bin/gvpr -f gvprstringBug1.gvpr

BEGIN{
  int   i=99;
  float f=76.3;
  string A, B, Z;

  void doPrnt(string errString) {
    print(errString);
  }
  
  A=" five ";
 
  doPrnt("one " + "two " + "three");  // yea, something works
  doPrnt("one " + A + "three");
  doPrnt((string)(i));
  // try the fallback - sprintf  (it fails, too)
  doPrnt(sprintf("%s\n", "Constant"));  
}

Expected Behaviour

happy, readable strings printed to sdtout (for this example)

Actual Behaviour

unprintable characters to stdout

OS Version

Linux mine 5.4.0-96-generic #109 (closed)-Ubuntu SMP Wed Jan 12 16:49:16 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Graphviz Version

dot - graphviz version 3.0.0~dev.20220120.0312 (20220120.0312)

Additional info

Fill in with anything else that might be important.