diff --git a/src/PhpSpreadsheet/Calculation/TextData/Replace.php b/src/PhpSpreadsheet/Calculation/TextData/Replace.php
index 1515864659..3c9bed539e 100644
--- a/src/PhpSpreadsheet/Calculation/TextData/Replace.php
+++ b/src/PhpSpreadsheet/Calculation/TextData/Replace.php
@@ -113,6 +113,6 @@ private static function executeSubstitution(string $text, string $fromText, stri
             --$instance;
         }
 
-        return Functions::scalar(self::REPLACE($text, ++$pos, StringHelper::countCharacters($fromText), $toText));
+        return (string) Functions::scalar(self::REPLACE($text, ++$pos, StringHelper::countCharacters($fromText), $toText));
     }
 }
diff --git a/src/PhpSpreadsheet/Chart/Layout.php b/src/PhpSpreadsheet/Chart/Layout.php
index f64f53319b..2b2175fe69 100644
--- a/src/PhpSpreadsheet/Chart/Layout.php
+++ b/src/PhpSpreadsheet/Chart/Layout.php
@@ -486,9 +486,9 @@ public function setLabelFontColor(?ChartColor $chartColor): self
     {
         if ($this->labelFont === null) {
             $this->labelFont = new Font();
-            $this->labelFont->setSize(null, true);
+            $this->labelFont->/** @scrutinizer ignore-call */ setSize(null, true);
         }
-        $this->labelFont->setChartColorFromObject($chartColor);
+        $this->labelFont->/** @scrutinizer ignore-call */ setChartColorFromObject($chartColor);
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/Helper/Downloader.php b/src/PhpSpreadsheet/Helper/Downloader.php
index 4e98c7925c..4eafe0238c 100644
--- a/src/PhpSpreadsheet/Helper/Downloader.php
+++ b/src/PhpSpreadsheet/Helper/Downloader.php
@@ -40,10 +40,11 @@ public function __construct(string $folder, string $filename, ?string $filetype
         }
 
         $filetype ??= pathinfo($filename, PATHINFO_EXTENSION);
-        if (array_key_exists(strtolower($filetype), self::CONTENT_TYPES) === false) {
+        $filetypeLower = strtolower(/** @scrutinizer ignore-type */ $filetype);
+        if (array_key_exists($filetypeLower, self::CONTENT_TYPES) === false) {
             throw new Exception("Invalid filetype: {$filetype} cannot be downloaded");
         }
-        $this->filetype = strtolower($filetype);
+        $this->filetype = $filetypeLower;
     }
 
     public function download(): void
diff --git a/src/PhpSpreadsheet/Helper/Sample.php b/src/PhpSpreadsheet/Helper/Sample.php
index fb40dd884e..d632635073 100644
--- a/src/PhpSpreadsheet/Helper/Sample.php
+++ b/src/PhpSpreadsheet/Helper/Sample.php
@@ -132,7 +132,7 @@ public function write(Spreadsheet $spreadsheet, $filename, array $writers = ['Xl
             $this->logWrite($writer, $path, /** @scrutinizer ignore-type */ $callStartTime);
             if ($this->isCli() === false) {
                 // @codeCoverageIgnoreStart
-                echo '<a href="/download.php?type=' . pathinfo($path, PATHINFO_EXTENSION) . '&name=' . basename($path) . '">Download ' . basename($path) . '</a><br />';
+                echo '<a href="/download.php?type=' . /** @scrutinizer ignore-type */ pathinfo($path, PATHINFO_EXTENSION) . '&name=' . basename($path) . '">Download ' . basename($path) . '</a><br />';
                 // @codeCoverageIgnoreEnd
             }
         }
diff --git a/src/PhpSpreadsheet/IOFactory.php b/src/PhpSpreadsheet/IOFactory.php
index 454b2aae40..ace60f381a 100644
--- a/src/PhpSpreadsheet/IOFactory.php
+++ b/src/PhpSpreadsheet/IOFactory.php
@@ -146,7 +146,7 @@ public static function createReaderForFile(string $filename, ?array $readers = n
 
         // First, lucky guess by inspecting file extension
         $guessedReader = self::getReaderTypeFromExtension($filename);
-        if (($guessedReader !== null) && array_key_exists($guessedReader, $testReaders)) {
+        if (array_key_exists($guessedReader, $testReaders)) {
             $reader = self::createReader($guessedReader);
 
             // Let's see if we are lucky
@@ -173,11 +173,11 @@ public static function createReaderForFile(string $filename, ?array $readers = n
     /**
      * Guess a reader type from the file extension, if any.
      */
-    private static function getReaderTypeFromExtension(string $filename): ?string
+    private static function getReaderTypeFromExtension(string $filename): string
     {
         $pathinfo = pathinfo($filename);
         if (!isset($pathinfo['extension'])) {
-            return null;
+            return '';
         }
 
         return match (strtolower($pathinfo['extension'])) {
@@ -205,8 +205,8 @@ private static function getReaderTypeFromExtension(string $filename): ?string
             // Do nothing
             // We must not try to use CSV reader since it loads
             // all files including Excel files etc.
-            'csv' => null,
-            default => null,
+            'csv' => '',
+            default => '',
         };
     }
 
diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index 7f29194d9d..d1aa64cb49 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -498,7 +498,7 @@ protected function loadSpreadsheetFromFile(string $filename): Spreadsheet
         $rels = $this->loadZip(self::INITIAL_FILE, Namespaces::RELATIONSHIPS);
 
         $propertyReader = new PropertyReader($this->getSecurityScannerOrThrow(), $excel->getProperties());
-        $chartDetails = [];
+        $charts = $chartDetails = [];
         foreach ($rels->Relationship as $relx) {
             $rel = self::getAttributes($relx);
             $relTarget = (string) $rel['Target'];
diff --git a/src/PhpSpreadsheet/Shared/Drawing.php b/src/PhpSpreadsheet/Shared/Drawing.php
index edaad86153..eba152cd53 100644
--- a/src/PhpSpreadsheet/Shared/Drawing.php
+++ b/src/PhpSpreadsheet/Shared/Drawing.php
@@ -166,7 +166,7 @@ public static function angleToDegrees($angle): int
     public static function imagecreatefrombmp($bmpFilename): GdImage
     {
         $retVal = @imagecreatefrombmp($bmpFilename);
-        if ($retVal === false) {
+        if (!($retVal instanceof GdImage)) {
             throw new ReaderException("Unable to create image from $bmpFilename");
         }
 
diff --git a/src/PhpSpreadsheet/Style/ConditionalFormatting/CellMatcher.php b/src/PhpSpreadsheet/Style/ConditionalFormatting/CellMatcher.php
index 3c815e4ac7..08671d9b09 100644
--- a/src/PhpSpreadsheet/Style/ConditionalFormatting/CellMatcher.php
+++ b/src/PhpSpreadsheet/Style/ConditionalFormatting/CellMatcher.php
@@ -262,7 +262,7 @@ protected function processDuplicatesComparison(Conditional $conditional): bool
             self::COMPARISON_DUPLICATES_OPERATORS[$conditional->getConditionType()],
             $worksheetName,
             $this->conditionalRange,
-            $this->cellConditionCheck($this->cell->getCalculatedValue())
+            $this->cellConditionCheck(/** @scrutinizer ignore-type */ $this->cell->getCalculatedValue())
         );
 
         return $this->evaluateExpression($expression);
diff --git a/src/PhpSpreadsheet/Worksheet/BaseDrawing.php b/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
index f25b050656..fa82ef6a5c 100644
--- a/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
+++ b/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
@@ -214,8 +214,8 @@ public function setWorksheet(?Worksheet $worksheet = null, bool $overrideOld = f
             // Add drawing to \PhpOffice\PhpSpreadsheet\Worksheet\Worksheet
             if ($worksheet !== null) {
                 $this->worksheet = $worksheet;
-                $this->worksheet->getCell($this->coordinates);
-                $this->worksheet->getDrawingCollection()->append($this);
+                $worksheet->getCell($this->coordinates);
+                $worksheet->getDrawingCollection()->append($this);
             }
         } else {
             if ($overrideOld) {
diff --git a/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php b/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
index 817816b191..b391035300 100644
--- a/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
+++ b/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
@@ -63,8 +63,9 @@ public function __construct()
     public function __destruct()
     {
         if ($this->imageResource) {
-            @imagedestroy($this->imageResource);
-            $this->imageResource = null;
+            $nullValue = null;
+            $rc = @imagedestroy($this->imageResource);
+            $this->imageResource = $rc ? null : $nullValue;
         }
         $this->worksheet = null;
     }
@@ -156,7 +157,7 @@ public static function fromString(string $imageString): self
         $renderingFunction = self::identifyRenderingFunction($mimeType);
 
         $drawing = new self();
-        $drawing->setImageResource($gdImage);
+        $drawing->setImageResource(/** @scrutinizer ignore-type */ $gdImage);
         $drawing->setRenderingFunction($renderingFunction);
         $drawing->setMimeType($mimeType);
 
diff --git a/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php b/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
index 6c01911c4e..23904ef237 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
@@ -1311,15 +1311,14 @@ private function writeCellFormula(XMLWriter $objWriter, string $cellValue, Cell
             $objWriter->endElement();
         } else {
             $objWriter->writeElement('f', FunctionPrefix::addFunctionPrefixStripEquals($cellValue));
-            self::writeElementIf(
-                $objWriter,
-                $this->getParentWriter()->getOffice2003Compatibility() === false
+            if (
+                $calculatedValue !== null
+                && !is_array($calculatedValue)
+                && $this->getParentWriter()->getOffice2003Compatibility() === false
                 && $this->getParentWriter()->getPreCalculateFormulas()
-                && $calculatedValue !== null,
-                'v',
-                (!is_array($calculatedValue) && !str_starts_with($calculatedValue ?? '', '#'))
-                    ? StringHelper::formatNumber($calculatedValue) : '0'
-            );
+            ) {
+                $objWriter->writeElement('v', StringHelper::formatNumber($calculatedValue));
+            }
         }
     }