Error message when displaying a MultivariateFormula

**Describe the bug**
In rstudio the following message is displayed after building a MultivariateFormula
```
Error in is.name(callee) && length(object) > 20 : 
  'length = 2' in coercion to 'logical(1)'
```

**To Reproduce**
`form <- multivariateFormula(a~b)`

**Expected behavior**
No error message

