Fix PHP notices.

bibcite_footnotes.module

@@ -112,7 +112,7 @@ function bibcite_footnotes_preprocess_bibcite_footnote_list(&$variables) {
       $override_page_in_citation = FALSE;
     }
 
-    if ($fn['ibid']) {
+    if (isset($fn['ibid']) && $fn['ibid']) {
       $build['footnote-text'] = [
         '#type' => 'markup',
         '#markup' => ' <span class="endnote-text"><span class="ibid">'
@@ -131,7 +131,7 @@ function bibcite_footnotes_preprocess_bibcite_footnote_list(&$variables) {
     }
 
     if (!empty($reference_entity_id)) {
-      if (!$fn['ibid']) {
+      if (empty($fn['ibid'])) {
         $citation_build = $citation_tools->getRenderableReference($reference_entity_id);
         if ($override_page_in_citation) {
           $citation_build['#data']['page'] = $override_page_in_citation;
@@ -200,5 +200,7 @@ function bibcite_footnotes_preprocess_bibcite_footnote_link(&$variables) {
   
 
   $link = Link::fromTextAndUrl($fn['value'], $url)->toRenderable();
-  $variables['fn']['fn'][] = $link;
+  unset($variables['fn']['fn']);
+  $variables['fn']['fn'] = $link;
+//  $variables['fn']['fn'][] = $link;
 }