message: Prevent failed ligature substitutions from being reported as ligatures
diff: @@ -152,13 +152,15 @@ class FontImpl implements Font {
  for (let i = nextLookup.first; i < lastGlyphIndex; i++) {
  const result = walkTree(lookup.tree, sequence, i, i);
  if (result) {
  + let didSubstitute = false;
  for (let j = 0; j < result.substitutions.length; j++) {
  const sub = result.substitutions[j];
  if (sub !== null) {
  sequence[i + j] = sub;
  + didSubstitute = true;
  }
  }
  -
  + if (didSubstitute) {
  mergeRange(
  ranges,
  result.contextRange[0] + i,
  @@ -169,7 +171,7 @@ class FontImpl implements Font {
  if (i + result.length >= lastGlyphIndex) {
  lastGlyphIndex = i + result.length + 1;
  }
  -
  + }
  i += result.length - 1;
  }
  }
  