Warning: Undefined array key

@bobjoe, I have fixed the issue and created MR. please review it once

@abhishek_gupta1 thank you! I just tested it and it seems as all the error messages are gone. Except the one regarding the select_or_other module:

Warning: Undefined array key "#other_option" in Drupal\select_or_other\Element\ElementBase::addSelectField() (Zeile 141 in /app/web/modules/contrib/select_or_other/src/Element/ElementBase.php).:
Called from <ROOT>/modules/contrib/select_or_other/src/Element/ElementBase.php:141 [backtrace_error_handler()]

I saw you created a patch for it already here: https://www.drupal.org/project/podcast/issues/3437811 🐛 Warnings related to the copyright field Needs work but I couldn't install it on top of your branch that fixes the specific issue on this page right here. I tried to install it on top of the current stable release of the podcast module, which worked, buts didn't solve the error message for me.

MR 13 doesn't fix these errors on my installation:

Warning: Trying to access array offset on value of type null in {closure}() (Zeile 73 in /app/web/modules/contrib/podcast/podcast.module).:
array (39)
Called from <ROOT>/modules/contrib/podcast/podcast.module:73 [backtrace_error_handler()]

Warning: Trying to access array offset on value of type null in {closure}() (Zeile 77 in /app/web/modules/contrib/podcast/podcast.module).:
array (39)
Called from <ROOT>/modules/contrib/podcast/podcast.module:77 [backtrace_error_handler()]

If I put a check for $value around that section, the errors go away, but I'm not familiar enough with the code to really understand what that does.

+    if ($value) {
+      if ($content = $value['value']) {
+        $out .= sprintf('<%s>%s</%s>', $value['key'], $content, $value['key']);
+      }
+      else {
+        $out .= sprintf('<%s />', $value['key']);
+      }
+      return $out;
     }
-    return $out;

Thanks for your work!