fix: simplify type guard in compareDeepIfVisited — drop redundant isObjectNotArray(a) check

Author: fgenois-coveo

lib/mergeDeep.js

@@ -248,7 +248,9 @@ class MergeDeep {
       modifications.push({})
       additions.push({})
       deletions.push({})
-      if (this.isObjectNotArray(visited[id]) && this.isObjectNotArray(a)) {
+      // visited[id] may be a primitive string (from the non-object branch in processArrays)
+      // — only deep-compare when both sides are real objects
+      if (this.isObjectNotArray(visited[id])) {
         // Strip the identity field before comparing — it was already used for matching
         const idPropA = NAME_USERNAME_PROPERTY(a)
         const idPropV = NAME_USERNAME_PROPERTY(visited[id])