Fixed some static-analysis issues and set a baseline for the single r…

…emaing issue

psalm-baseline.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<files psalm-version="3.9.5@0cfe565d0afbcd31eadcc281b9017b5692911661">
+  <file src="src/Traits/Transformable.php">
+    <PossiblyNullArgument occurrences="1">
+      <code>$count</code>
+    </PossiblyNullArgument>
+  </file>
+</files>

psalm.xml

@@ -5,6 +5,7 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
     xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    errorBaseline="psalm-baseline.xml"
 >
     <projectFiles>
         <directory name="src" />

src/Traits/Encodable.php

@@ -73,7 +73,7 @@ public function hex(string $mode = Config\Hex::ENCODE): self
 
             case Config\Hex::DECODE:
                 $string = preg_replace_callback('/\\\\x([0-9A-Fa-f]+)/', function (array $matched) {
-                    return mb_chr(hexdec($matched[1]), $this->encoding);
+                    return (string) mb_chr(hexdec($matched[1]), $this->encoding);
                 }, $this->string);
                 break;
 

src/Traits/Transformable.php

@@ -41,7 +41,7 @@ public function reverse(): self
      *
      * @param string|array $search  One or more strings to be replaced
      * @param string|array $replace One or more strings to replace with
-     * @param int          $count   This will be set to the number of replacements performed
+     * @param int|null     $count   This will be set to the number of replacements performed
      *
      * @return self
      */