diff --git a/Algorithm/Clustering/DBSCAN.php b/Algorithm/Clustering/DBSCAN.php
index 09f011ef9..5596e2e7c 100644
--- a/Algorithm/Clustering/DBSCAN.php
+++ b/Algorithm/Clustering/DBSCAN.php
@@ -68,7 +68,7 @@ final class DBSCAN
      *
      * Array of points assigned to a cluster
      *
-     * @var array<int, array{x:float, y:float}>
+     * @var array<int, array>
      * @since 1.0.0
      */
     private array $clusters = [];
@@ -232,6 +232,7 @@ final class DBSCAN
                     $points[] = $p->coordinates;
                 }
 
+                // @todo: this is only good for 2D. Fix this for ND.
                 $this->convexHulls[$c] = MonotoneChain::createConvexHull($points);
             }
         }
diff --git a/DataStorage/Session/JWT.php b/DataStorage/Session/JWT.php
index 283651e03..9a6eb1694 100644
--- a/DataStorage/Session/JWT.php
+++ b/DataStorage/Session/JWT.php
@@ -106,7 +106,9 @@ final class JWT
             return [];
         }
 
-        return \json_decode(Base64Url::decode($explode[0]), true);
+        $json = \json_decode(Base64Url::decode($explode[0]), true);
+
+        return \is_array($json) ? $json : [];
     }
 
     /**
@@ -126,7 +128,9 @@ final class JWT
             return [];
         }
 
-        return \json_decode(Base64Url::decode($explode[1]), true);
+        $json = \json_decode(Base64Url::decode($explode[1]), true);
+
+        return \is_array($json) ? $json : [];
     }
 
     /**
@@ -150,6 +154,11 @@ final class JWT
         try {
             $header    = \json_decode(Base64Url::decode($explode[0]), true);
             $payload   = \json_decode(Base64Url::decode($explode[1]), true);
+
+            if (!\is_array($header) || !\is_array($payload)) {
+                return false;
+            }
+
             $signature = self::createSignature($secret, $header, $payload);
 
             return \hash_equals($signature, $explode[2]);
diff --git a/Localization/LanguageDetection/LanguageResult.php b/Localization/LanguageDetection/LanguageResult.php
index 6b76f4067..c1bbce596 100755
--- a/Localization/LanguageDetection/LanguageResult.php
+++ b/Localization/LanguageDetection/LanguageResult.php
@@ -73,6 +73,7 @@ class LanguageResult implements \ArrayAccess, \IteratorAggregate, \JsonSerializa
      */
     public function offsetSet($offset, $value) : void
     {
+        /** @var float|int $value */
         if ($offset === null) {
             $this->result[] = $value;
         } else {
diff --git a/Localization/LanguageDetection/NgramParser.php b/Localization/LanguageDetection/NgramParser.php
index d6a9f1eca..f8002150d 100755
--- a/Localization/LanguageDetection/NgramParser.php
+++ b/Localization/LanguageDetection/NgramParser.php
@@ -101,6 +101,7 @@ abstract class NgramParser
             }
         }
 
+        /** @var array $tokens */
         foreach ($tokens as $i => $token) {
             $sum = \array_sum($token);
 
diff --git a/Math/Matrix/Matrix.php b/Math/Matrix/Matrix.php
index 2a7cca7b4..e678a0cf8 100755
--- a/Math/Matrix/Matrix.php
+++ b/Math/Matrix/Matrix.php
@@ -697,11 +697,11 @@ class Matrix implements \ArrayAccess, \Iterator
      *
      * @param self $B Matrix
      *
-     * @return self
+     * @return int|float|self
      *
      * @since 1.0.0
      */
-    public function dot(self $B) : self
+    public function dot(self $B) : int|float|self
     {
         $value1 = $this->matrix;
         $value2 = $B->getMatrix();
@@ -731,6 +731,8 @@ class Matrix implements \ArrayAccess, \Iterator
                     $result[$i][$c] = $temp;
                 }
             }
+
+            return self::fromArray($result);
         } elseif (!$isMatrix1 && !$isMatrix2) {
             if ($m1 !== $m2) {
                 throw new InvalidDimensionException($m1 . 'x' . $m2);
@@ -742,6 +744,8 @@ class Matrix implements \ArrayAccess, \Iterator
                 /** @var array $value2 */
                 $result += $value1[$i] * $value2[$i];
             }
+
+            return $result;
         } elseif ($isMatrix1 && !$isMatrix2) {
             $result = [];
             for ($i = 0; $i < $m1; ++$i) { // Row of 1
@@ -754,11 +758,11 @@ class Matrix implements \ArrayAccess, \Iterator
 
                 $result[$i] = $temp;
             }
-        } else {
-            throw new \InvalidArgumentException();
+
+            return self::fromArray($result);
         }
 
-        return self::fromArray($result);
+        throw new \InvalidArgumentException();
     }
 
     /**
diff --git a/Math/Matrix/Vector.php b/Math/Matrix/Vector.php
index 662b1f614..46fb214f5 100755
--- a/Math/Matrix/Vector.php
+++ b/Math/Matrix/Vector.php
@@ -101,7 +101,7 @@ final class Vector extends Matrix
     {
         $dotProduct = 0.0;
         for ($i = 0; $i < $this->m; ++$i) {
-            $dotProduct += $this->matrix[$i][0] * $v[$i];
+            $dotProduct += $this->matrix[$i][0] * $v[$i][0];
         }
 
         $sumOfSquares = 0;
@@ -116,7 +116,7 @@ final class Vector extends Matrix
         }
         $magnitude2 = \sqrt($sumOfSquares);
 
-        if ($magnitude1 === 0 || $magnitude2 === 0) {
+        if ($magnitude1 === 0.0 || $magnitude2 === 0.0) {
             return \PHP_FLOAT_MAX;
         }
 
diff --git a/Stdlib/Graph/Graph.php b/Stdlib/Graph/Graph.php
index 137192abc..2d6f0fffd 100755
--- a/Stdlib/Graph/Graph.php
+++ b/Stdlib/Graph/Graph.php
@@ -583,7 +583,7 @@ class Graph
 
         while (!empty($stack)) {
             $cNode = \array_pop($stack);
-            if (isset($visited[$cNode->getId()]) && $visited[$cNode->getId()]) {
+            if (isset($visited[$cNode->getId()])) {
                 continue;
             }
 
@@ -592,7 +592,7 @@ class Graph
 
             $neighbors = $cNode->getNeighbors();
             foreach ($neighbors as $neighbor) {
-                if (!isset($visited[$neighbor->getId()]) || !$visited[$neighbor->getId()]) {
+                if (!isset($visited[$neighbor->getId()])) {
                     $stack[] = $neighbor;
                 }
             }
diff --git a/Utils/ArrayUtils.php b/Utils/ArrayUtils.php
index e704f4b2a..6ed578f26 100755
--- a/Utils/ArrayUtils.php
+++ b/Utils/ArrayUtils.php
@@ -311,17 +311,21 @@ final class ArrayUtils
      */
     public static function getArg(string $id, array $args) : mixed
     {
+        $key = 0;
         if (\is_numeric($id)) {
-            return $args[(int) $id] ?? null;
+            $key = ((int) $id) - 1;
+        } else {
+            if (($key = \array_search($id, $args)) === false || $key === \count($args) - 1) {
+                return null;
+            }
+
+            $key  = (int) $key;
+            $args = \array_values($args);
         }
 
-        if (($key = \array_search($id, $args)) === false || $key === \count($args) - 1) {
-            return null;
-        }
+        $value = $args[$key + 1] ?? null;
 
-        $value = $args[(int) $key + 1];
-
-        return \is_string($value) ? \trim($value, '" ') : $value;
+        return \is_string($value) ? \trim($value, '\'" ') : $value;
     }
 
     /**
@@ -336,7 +340,6 @@ final class ArrayUtils
      */
     public static function hasArg(string $id, array $args) : int
     {
-        $t = \array_search($id, $args);
         return ($key = \array_search($id, $args)) === false
             ? -1
             : (int) $key;
diff --git a/Utils/Barcode/Datamatrix.php b/Utils/Barcode/Datamatrix.php
index 101505d0b..c9c8c2cbd 100755
--- a/Utils/Barcode/Datamatrix.php
+++ b/Utils/Barcode/Datamatrix.php
@@ -613,7 +613,8 @@ class Datamatrix extends TwoDAbstract
 
                             if ($this->isCharMode($tmpchr, self::ENC_X12)) {
                                 return self::ENC_X12;
-                            } elseif (!$this->isCharMode($tmpchr, self::ENC_X12) && !$this->isCharMode($tmpchr, self::ENC_C40)
+                            } elseif (!$this->isCharMode($tmpchr, self::ENC_X12)
+                                && !$this->isCharMode($tmpchr, self::ENC_C40)
                             ) {
                                 break;
                             }
diff --git a/tests/Algorithm/Clustering/KmeansTest.php b/tests/Algorithm/Clustering/KmeansTest.php
index d2743815a..5a2a30a40 100755
--- a/tests/Algorithm/Clustering/KmeansTest.php
+++ b/tests/Algorithm/Clustering/KmeansTest.php
@@ -48,7 +48,8 @@ final class KmeansTest extends \PHPUnit\Framework\TestCase
                 new Point([3.5, 4.5], '7'),
             ];
 
-            $kmeans = new Kmeans($points, 2);
+            $kmeans = new Kmeans();
+            $kmeans->generateClusters($points, 2);
 
             if ($kmeans->cluster($points[0])->group === 0
                 && $kmeans->cluster($points[1])->group === 0