Program: 135903
Project: 135903
Buggy source:
protected Assignment doEditFormula(Assignment formula){
  if (formula == null) {
    String[] names=null;
    Object input=this.getTableViewer().getInput();
    if ((input != null) && (input instanceof Vector)) {
      Vector inputVec=(Vector)input;
      names=new String[inputVec.size()];
      for (int i=0; i < names.length; i++) {
        Object next=inputVec.elementAt(i);
        if ((next != null) && (next instanceof Assignment)) {
          Assignment nextAss=(Assignment)next;
          names[i]=nextAss.getLabel();
        }
 else {
          names[i]="String_Node_Str";
        }
      }
    }
 else {
      names=new String[0];
    }
    FilteredDefinitionSelectionDialog definitionSelection=new FilteredDefinitionSelectionDialog(this.getSection().getShell(),false,ToolboxHandle.getCurrentSpec().getValidRootModule(),names);
    definitionSelection.setTitle("String_Node_Str");
    definitionSelection.setMessage("String_Node_Str");
    definitionSelection.setInitialPattern("String_Node_Str");
    if (Window.OK == definitionSelection.open()) {
      OpDefNode result=(OpDefNode)(definitionSelection.getResult())[0];
      formula=new Assignment(result.getName().toString(),Assignment.getArrayOfEmptyStrings(result.getSource().getNumberOfArgs()),"String_Node_Str");
    }
 else {
      return null;
    }
  }
  OpDefNode opDefNode=(OpDefNode)ModelHelper.getOpDefNode(formula.getLabel());
  if (opDefNode != null && opDefNode.getSource().getNumberOfArgs() != formula.getParams().length) {
    String[] newParams=new String[opDefNode.getSource().getNumberOfArgs()];
    for (int i=0; i < newParams.length; i++) {
      newParams[i]="String_Node_Str";
    }
    formula.setParams(newParams);
  }
  AssignmentWizard wizard=new AssignmentWizard(getSection().getText(),getSection().getDescription(),(Assignment)formula,AssignmentWizard.SHOW_MODEL_VALUE_OPTION,AssignmentWizardPage.DEF_OVERRIDE_WIZARD_ID,"String_Node_Str");
  WizardDialog dialog=new WizardDialog(getTableViewer().getTable().getShell(),wizard);
  dialog.setHelpAvailable(true);
  if (Window.OK == dialog.open()) {
    return wizard.getFormula();
  }
 else {
    return null;
  }
}

Fixed version (ground truth):
protected Assignment doEditFormula(Assignment formula){
  if (formula == null) {
    String[] names=null;
    Object input=this.getTableViewer().getInput();
    if ((input != null) && (input instanceof Vector)) {
      Vector inputVec=(Vector)input;
      names=new String[inputVec.size()];
      for (int i=0; i < names.length; i++) {
        Object next=inputVec.elementAt(i);
        if ((next != null) && (next instanceof Assignment)) {
          Assignment nextAss=(Assignment)next;
          names[i]=nextAss.getLabel();
        }
 else {
          names[i]="String_Node_Str";
        }
      }
    }
 else {
      names=new String[0];
    }
    FilteredDefinitionSelectionDialog definitionSelection=new FilteredDefinitionSelectionDialog(this.getSection().getShell(),false,ToolboxHandle.getCurrentSpec().getValidRootModule(),names);
    definitionSelection.setTitle("String_Node_Str");
    definitionSelection.setMessage("String_Node_Str");
    definitionSelection.setInitialPattern("String_Node_Str");
    if (Window.OK == definitionSelection.open()) {
      OpDefNode result=(OpDefNode)(definitionSelection.getResult())[0];
      formula=new Assignment(result.getName().toString(),Assignment.getArrayOfEmptyStrings(result.getSource().getNumberOfArgs()),"String_Node_Str");
    }
 else {
      return null;
    }
  }
  OpDefNode opDefNode=(OpDefNode)ModelHelper.getOpDefNode(formula.getLabel());
  if (opDefNode != null && opDefNode.getSource().getNumberOfArgs() != formula.getParams().length) {
    String[] newParams=new String[opDefNode.getSource().getNumberOfArgs()];
    for (int i=0; i < newParams.length; i++) {
      newParams[i]="String_Node_Str";
    }
    formula.setParams(newParams);
  }
  AssignmentWizard wizard=new AssignmentWizard(getSection().getText(),getSection().getDescription(),(Assignment)formula,AssignmentWizard.SHOW_MODEL_VALUE_OPTION,AssignmentWizardPage.DEF_OVERRIDE_WIZARD_ID,"String_Node_Str");
  WizardDialog dialog=new WizardDialog(getTableViewer().getTable().getShell(),wizard);
  wizard.setWizardDialog(dialog);
  dialog.setHelpAvailable(true);
  if (Window.OK == dialog.open()) {
    return wizard.getFormula();
  }
 else {
    return null;
  }
}