check preg_replace for null results

Author: SjorsO

src/Property/Selector.php

@@ -184,8 +184,16 @@ public function setSelector(string $selector): void
         $hasAttribute = \strpos($selector, '[') !== false;
 
         // Whitespace can't be adjusted within an attribute selector, as it would change its meaning
-        /** @phpstan-ignore theCodingMachineSafe.function */
-        $this->selector = !$hasAttribute ? \preg_replace('/\\s++/', ' ', $selector) : $selector;
+        if ($hasAttribute) {
+            $this->selector = $selector;
+        } else {
+            /** @phpstan-ignore theCodingMachineSafe.function */
+            $normalized = \preg_replace('/\\s++/', ' ', $selector);
+            if ($normalized === null) {
+                throw new \RuntimeException('Unexpected error');
+            }
+            $this->selector = $normalized;
+        }
     }
 
     /**

src/Value/Size.php

@@ -202,13 +202,22 @@ public function render(OutputFormat $outputFormat): string
         if ($matchResult === false) {
             throw new \RuntimeException('Unexpected error');
         }
-        $size = $matchResult === 1
+        if ($matchResult === 1) {
             /** @phpstan-ignore theCodingMachineSafe.function */
-            ? \preg_replace("/$decimalPoint?0+$/", '', \sprintf('%f', $this->size))
-            : (string) $this->size;
+            $size = \preg_replace("/$decimalPoint?0+$/", '', \sprintf('%f', $this->size));
+            if ($size === null) {
+                throw new \RuntimeException('Unexpected error');
+            }
+        } else {
+            $size = (string) $this->size;
+        }
 
         /** @phpstan-ignore theCodingMachineSafe.function */
-        return \preg_replace(["/$decimalPoint/", '/^(-?)0\\./'], ['.', '$1.'], $size) . ($this->unit ?? '');
+        $result = \preg_replace(["/$decimalPoint/", '/^(-?)0\\./'], ['.', '$1.'], $size);
+        if ($result === null) {
+            throw new \RuntimeException('Unexpected error');
+        }
+        return $result . ($this->unit ?? '');
     }
 
     /**