message: chore: fix types, clarify the intent with a comment
diff: @@ -10,10 +10,15 @@ export function isSequenced(pos: number, seq: AnalysisResultWithoutClade) {
  export function calculate_distance(node: AuspiceTreeNodeExtended, seq: AnalysisResultWithoutClade) {
  let shared_differences = 0
  let shared_sites = 0
  - const nodeSubstitutions: MutationMap = new Map()
  +
  + // Filter-out gaps, to prevent double counting
  + const nodeSubstitutions: MutationMap = new Map<number, Nucleotide>()
  node.mutations?.forEach((v, k) => {
  - if (v !== '-') nodeSubstitutions.set(k, v)
  + if (v !== '-') {
  + nodeSubstitutions.set(k, v)
  + }
  })
  +
  for (const qmut of seq.substitutions) {
  const der = nodeSubstitutions?.get(qmut.pos)
  if (der) {
  