fixup! schemaloader: Fix expandRefs not to crash if $ref'ed schema al…

…so has another $ref to self internally

Testing via CodecepJS and reference.html revealed a bug in my second
patch: if the ref is of the form

    schema.json#/json/pointer1#/json/pointer2

we need to load schema.json, dereference pointer1 and then dereference
pointer2 on the result.

Original code was doing this second step, but my patch did not, and so
it was breaking as e.g.:

https://github.com/json-editor/json-editor/actions/runs/6074053135/job/16477372582#step:6:456

src/schemaloader.js

@@ -166,31 +166,37 @@ export class SchemaLoader {
     const refObj = (refWithPointerSplit.length > 2)
       ? this.refs_with_info['#' + refWithPointerSplit[1]]
       : this.refs_with_info[_schema.$ref]
+    const refPointersTail = refWithPointerSplit.slice(2)
     delete _schema.$ref
     const fetchUrl = refObj.$ref.startsWith('#')
       ? refObj.fetchUrl
       : ''
     const ref = this._getRef(fetchUrl, refObj)
 
+    // lookup schema via .refs[refBase] and dereference via JSON-pointer from ref
     refWithPointerSplit = ref.split('#')
     let refBase = ref
-    let refPointer = null
+    let refPointers = []
     if (refWithPointerSplit.length > 1) {
       refBase = refWithPointerSplit[0]
-      refPointer = refWithPointerSplit[1]
+      refPointers = refWithPointerSplit.slice(1)
     }
-
     if (!this.refs[refBase]) { /* if reference not found */
       // eslint-disable-next-line no-console
       console.warn(`reference:'${ref}' not found!`)
     }
-
     let refSchema = this.refs[refBase]
-    if (refPointer !== null) {
-      refSchema = this.expandRecursivePointer(refSchema, refPointer)
+    while (refPointers.length > 0) {
+      refSchema = this.expandRecursivePointer(refSchema, refPointers.shift())
     }
+
+    // further expand JSON-pointer from tail of original fragment [2, ...]
+    while (refPointersTail.length > 0) {
+      refSchema = this.expandRecursivePointer(refSchema, refPointersTail.shift())
+    }
+
     if (recurseAllOf && hasOwnProperty(refSchema, 'allOf')) {
-      const allOf = this.refs[ref].allOf
+      const allOf = refSchema.allOf
       Object.keys(allOf).forEach(key => {
         allOf[key] = this.expandRefs(allOf[key], true)
       })