[6.x] Fix replicator preview text merging during reorder (#14072)

Fix replicator preview text merging fields from different set types during reorder

When drag-and-drop reordering replicator sets of different types, the
collapsed preview text incorrectly merged fields from multiple set types.
This happened because stale preview entries from the old set type remained
at index-based paths, and the previewText filter failed to exclude fields
that don't belong to the current set type — when a field handle wasn't
found in the set's config, it fell back to {} and {}.replicator_preview
=== undefined evaluated to true, letting foreign fields pass through.

Now when a field handle is not found in the current set's config, it
returns false immediately, filtering out any stale foreign-type fields.

Fixes #14071

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: dannyuk1982

resources/js/components/fieldtypes/replicator/ManagesPreviewText.js

@@ -7,7 +7,8 @@ export default {
                 .filter(([handle, value]) => {
                     if (!handle.endsWith('_')) return false;
                     handle = handle.substr(0, handle.length - 1); // Remove the trailing underscore.
-                    const config = this.config.fields.find((f) => f.handle === handle) || {};
+                    const config = this.config.fields.find((f) => f.handle === handle);
+                    if (!config) return false;
                     return config.replicator_preview === undefined ? this.showFieldPreviews : config.replicator_preview;
                 })
                 .map(([handle, value]) => value)

resources/js/components/fieldtypes/replicator/Set.vue

@@ -83,7 +83,8 @@ const previewText = computed(() => {
         .filter(([handle, value]) => {
             if (!handle.endsWith('_')) return false;
             handle = handle.substr(0, handle.length - 1); // Remove the trailing underscore.
-            const config = props.config.fields.find((f) => f.handle === handle) || {};
+            const config = props.config.fields.find((f) => f.handle === handle);
+            if (!config) return false;
             return config.replicator_preview === undefined ? props.showFieldPreviews : config.replicator_preview;
         })
         .map(([handle, value]) => value)