Warning: avoid-slur not set

[Jonathan Armitage]

Hi everyone,

When I compile the following:

\version "2.20.0"

\language "english"

 #(define RH rightHandFinger)
 
music = {
    \set fingeringOrientations = #'(left)
    \set strokeFingerOrientations = #'(up)
    \key d \major
     \stemDown
    <e'-1\RH #2 >( <fs-3>) <a-1> fs
}

\score {
    \new Staff \relative c' {
        \new Voice = "whatever" { \music }
    }
    \layout {}
}

...I get the warning "Ignoring grob for StrokeFinger: avoid-slur not set?"

I can see that the slur clashes with the i, but in spite of much googling, I cannot for the life of me figure out how to set avoid-slur. Please could you advise.

Jon