Warning: array_key_exists(): The first argument should be either a string or an integer in Drupal\easy_breadcrumb\EasyBreadcrumbBuilder->build() (line 240 of /<path to docroot>/modules/contrib/easy_breadcrumb/src/EasyBreadcrumbBuilder.php)

This was caused by html inside menu links. Fixed by the following patch. Warning: this patch will strip numeric values and html from the menulink (only in the breadcrumb of course)

Index: web/modules/contrib/easy_breadcrumb/src/EasyBreadcrumbBuilder.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- web/modules/contrib/easy_breadcrumb/src/EasyBreadcrumbBuilder.php	(date 1578391614392)
+++ web/modules/contrib/easy_breadcrumb/src/EasyBreadcrumbBuilder.php	(date 1578391614392)
@@ -409,8 +409,12 @@
               else {
                 $menu_link = reset($menu_links);
                 $title = $menu_link->getTitle();
-                if (array_key_exists($title, $replacedTitles)) {
-                  $title = $replacedTitles[$title];
+                if(is_object($title)) {
+                  $title = strip_tags(preg_replace('/[0-9]+/', '', $title->render()));
+                } else {
+                  if (array_key_exists($title, $replacedTitles)) {
+                    $title = $replacedTitles[$title];
+                  }
                 }
               }
             }