Refined Pages instance

new getFonts method not only
returned stored fonts but also built related fonts
list. With this changes its easier to test and the
replacement (setupFonts) only builds the fonts list.
    
Also refined some phpdoc comments.

src/Smalot/PdfParser/Pages.php

@@ -40,7 +40,7 @@
 class Pages extends PDFObject
 {
     /**
-     * @var Font[]
+     * @var array<\Smalot\PdfParser\Font>|null
      */
     protected $fonts;
 
@@ -63,7 +63,10 @@ public function getPages(bool $deep = false): array
         }
 
         // Prepare to apply the Pages' object's fonts to each page
-        $fonts = $this->getFonts();
+        if (false === \is_array($this->fonts)) {
+            $this->setupFonts();
+        }
+        $fontsAvailable = 0 < \count($this->fonts);
 
         $kids = $kidsElement->getContent();
         $pages = [];
@@ -72,8 +75,8 @@ public function getPages(bool $deep = false): array
             if ($kid instanceof self) {
                 $pages = array_merge($pages, $kid->getPages(true));
             } elseif ($kid instanceof Page) {
-                if (!empty($this->fonts)) {
-                    $kid->setFonts($fonts);
+                if ($fontsAvailable) {
+                    $kid->setFonts($this->fonts);
                 }
                 $pages[] = $kid;
             }
@@ -83,19 +86,18 @@ public function getPages(bool $deep = false): array
     }
 
     /**
-     * @return Font[]
+     * Gathers information about fonts and collects them in a list.
+     *
+     * @return void
      */
-    protected function getFonts()
+    protected function setupFonts()
     {
-        if (null !== $this->fonts) {
-            return $this->fonts;
-        }
-
         $resources = $this->get('Resources');
 
         if (method_exists($resources, 'has') && $resources->has('Font')) {
+            // no fonts available, therefore stop here
             if ($resources->get('Font') instanceof Element\ElementMissing) {
-                return [];
+                return;
             }
 
             if ($resources->get('Font') instanceof Header) {
@@ -118,9 +120,9 @@ protected function getFonts()
                 }
             }
 
-            return $this->fonts = $table;
+            $this->fonts = $table;
+        } else {
+            $this->fonts = [];
         }
-
-        return [];
     }
 }