This might fix the missing stack trace. [skip ci]

resources/views/emails/error-html.twig

@@ -40,6 +40,6 @@
 <p style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;">
     The full stacktrace is below:</p>
 <p style="font-family: monospace;font-size:11px;color:#aaa">
-    {{ stacktrace|nl2br }}
+    {{ stackTrace|nl2br }}
 </p>
 {% include 'emails.footer-html' %}

resources/views/emails/error-text.twig

@@ -25,5 +25,5 @@ https://github.com/JC5/firefly-iii/issues/new
 
 The full stacktrace is below:
 
-{{ stacktrace }}
+{{ stackTrace }}
 {% include 'emails.footer-text' %}