A few more PHP8.1 fixes (#17989)

* add return type declartions #17686

should not break anything and gets rid of a warning

* add return type to method signature #17686

* annotate return types to avoid warnings

* add more return types

* upgrade phpmailer/phpmailer to 6.5.1

* add return types, avoid deprecated null to string conversion

* fix some deprecation warnings for php 8.1 #17686

* fix in DbHelper::getInstallVersion() instead #17686

* ensure empty(DbHelper::getInstallVersion()) succeed #17686

* force return "0" string and adjust test

Co-authored-by: Justin Velluppillai <justin@innocraft.com>

8 files changed, 10 insertions, 8 deletions

diff --git a/plugins/DevicePlugins/API.php b/plugins/DevicePlugins/API.php
index b767d5ade5..99109f72aa 100644
--- a/plugins/DevicePlugins/API.php
+++ b/plugins/DevicePlugins/API.php
@@ -86,6 +86,7 @@ class API extends \Piwik\Plugin\API
             $visitsSum = $visitsSumTotal - $ieVisits;
 
             $extraProcessedMetrics = $table->getMetadata(DataTable::EXTRA_PROCESSED_METRICS_METADATA_NAME);
+            $extraProcessedMetrics = is_array($extraProcessedMetrics) ? $extraProcessedMetrics : [];
             $extraProcessedMetrics[] = new VisitsPercent($visitsSum);
             $table->setMetadata(DataTable::EXTRA_PROCESSED_METRICS_METADATA_NAME, $extraProcessedMetrics);
         }
diff --git a/plugins/MultiSites/API.php b/plugins/MultiSites/API.php
index 5a12e71a0d..a0e20a470c 100644
--- a/plugins/MultiSites/API.php
+++ b/plugins/MultiSites/API.php
@@ -353,6 +353,7 @@ class API extends \Piwik\Plugin\API
                                       ? "Piwik\\Plugins\\MultiSites\\Columns\\Metrics\\EcommerceOnlyEvolutionMetric"
                                       : "Piwik\\Plugins\\CoreHome\\Columns\\Metrics\\EvolutionMetric";
 
+                $extraProcessedMetrics = is_array($extraProcessedMetrics) ? $extraProcessedMetrics : [];
                 $extraProcessedMetrics[] = new $evolutionMetricClass(
                     $metricSettings[self::METRIC_RECORD_NAME_KEY],
                     $pastData,
diff --git a/plugins/Referrers/VisitorDetails.php b/plugins/Referrers/VisitorDetails.php
index df571bf5f3..ece8dc40fe 100644
--- a/plugins/Referrers/VisitorDetails.php
+++ b/plugins/Referrers/VisitorDetails.php
@@ -94,9 +94,9 @@ class VisitorDetails extends VisitorDetailsAbstract
         return null;
     }
 
-    protected function getReferrerName()
+    protected function getReferrerName(): string
     {
-        return urldecode($this->details['referer_name']);
+        return urldecode($this->details['referer_name'] ?? '');
     }
 
     protected function getSearchEngineUrl()
diff --git a/plugins/SEO/Metric/Alexa.php b/plugins/SEO/Metric/Alexa.php
index b0d3a42c6b..a9a58160e0 100644
--- a/plugins/SEO/Metric/Alexa.php
+++ b/plugins/SEO/Metric/Alexa.php
@@ -35,7 +35,7 @@ class Alexa implements MetricsProvider
     {
         $value = null;
         try {
-            $response = Http::sendHttpRequest(self::URL . urlencode($domain), $timeout = 10, @$_SERVER['HTTP_USER_AGENT']);
+            $response = Http::sendHttpRequest(self::URL . urlencode($domain ?? ''), $timeout = 10, @$_SERVER['HTTP_USER_AGENT']);
             libxml_use_internal_errors(true); // suppress errors
             $dom = new \DomDocument();
             $dom->loadHTML($response);
@@ -54,7 +54,7 @@ class Alexa implements MetricsProvider
         }
 
         $logo = "plugins/Morpheus/icons/dist/SEO/alexa.com.png";
-        $link = self::LINK . urlencode($domain);
+        $link = self::LINK . urlencode($domain ?? '');
 
         return array(
             new Metric('alexa', 'SEO_AlexaRank', $value, $logo, $link)
diff --git a/plugins/SEO/Metric/Bing.php b/plugins/SEO/Metric/Bing.php
index ab7b1bce88..1279b77894 100644
--- a/plugins/SEO/Metric/Bing.php
+++ b/plugins/SEO/Metric/Bing.php
@@ -32,7 +32,7 @@ class Bing implements MetricsProvider
 
     public function getMetrics($domain)
     {
-        $url = self::URL . urlencode($domain);
+        $url = self::URL . urlencode($domain ?? '');
 
         try {
             $response = str_replace(' ', ' ', Http::sendHttpRequest($url, $timeout = 10, @$_SERVER['HTTP_USER_AGENT']));
diff --git a/plugins/SEO/Metric/DomainAge.php b/plugins/SEO/Metric/DomainAge.php
index 8d5d4bc4b8..0753e8eb89 100644
--- a/plugins/SEO/Metric/DomainAge.php
+++ b/plugins/SEO/Metric/DomainAge.php
@@ -35,7 +35,7 @@ class DomainAge implements MetricsProvider
 
     public function getMetrics($domain)
     {
-        $domain  = str_replace('www.', '', $domain);
+        $domain  = str_replace('www.', '', $domain ?? '');
 
         $ages = array();
 
diff --git a/plugins/SEO/Metric/Google.php b/plugins/SEO/Metric/Google.php
index 2edf5afc23..14f6e3d9f2 100644
--- a/plugins/SEO/Metric/Google.php
+++ b/plugins/SEO/Metric/Google.php
@@ -46,7 +46,7 @@ class Google implements MetricsProvider
 
     public function fetchIndexedPagesCount($domain)
     {
-        $url = self::SEARCH_URL . urlencode($domain);
+        $url = self::SEARCH_URL . urlencode($domain ?? '');
 
         try {
             $response = str_replace(' ', ' ', Http::sendHttpRequest($url, $timeout = 10, @$_SERVER['HTTP_USER_AGENT']));
diff --git a/plugins/SEO/Metric/ProviderCache.php b/plugins/SEO/Metric/ProviderCache.php
index 98b4c08fa0..898a19a6fd 100644
--- a/plugins/SEO/Metric/ProviderCache.php
+++ b/plugins/SEO/Metric/ProviderCache.php
@@ -34,7 +34,7 @@ class ProviderCache implements MetricsProvider
 
     public function getMetrics($domain)
     {
-        $cacheId = 'SEO_getRank_' . md5($domain);
+        $cacheId = 'SEO_getRank_' . md5($domain ?? '');
 
         $metrics = $this->cache->fetch($cacheId);