fix Overseerr homepage item does not read the username properly (#1915)

api/homepage/overseerr.php

@@ -164,7 +164,7 @@ trait OverseerrHomepageItem
 				$requestAll = [];
 				$requestsData = json_decode($request->body, true);
 				foreach ($requestsData['results'] as $key => $value) {
-					$requester = ($value['requestedBy']['username'] !== '') ? $value['requestedBy']['username'] : $value['requestedBy']['plexUsername'];
+					$requester = ($value['requestedBy']['username'] !== '' && $value['requestedBy']['username'] !== null) ? $value['requestedBy']['username'] : $value['requestedBy']['plexUsername'];
 					$requesterEmail = $value['requestedBy']['email'];
 					$proceed = (($this->config['overseerrLimitUser']) && strtolower($this->user['username']) == strtolower($requester)) || (strtolower($requester) == strtolower($this->config['overseerrFallbackUser'])) || (!$this->config['overseerrLimitUser']) || $this->qualifyRequest(1);
 					if ($proceed) {