Remove some implicit bool type juggling

Author: Girgias

UnicodeString.php

@@ -106,11 +106,13 @@ public function endsWith(string|iterable|AbstractString $suffix): bool
             return false;
         }
 
+        $grapheme = grapheme_extract($this->string, \strlen($suffix), \GRAPHEME_EXTR_MAXBYTES, \strlen($this->string) - \strlen($suffix)) ?: '';
+
         if ($this->ignoreCase) {
-            return 0 === mb_stripos(grapheme_extract($this->string, \strlen($suffix), \GRAPHEME_EXTR_MAXBYTES, \strlen($this->string) - \strlen($suffix)), $suffix, 0, 'UTF-8');
+            return 0 === mb_stripos($grapheme, $suffix, 0, 'UTF-8');
         }
 
-        return $suffix === grapheme_extract($this->string, \strlen($suffix), \GRAPHEME_EXTR_MAXBYTES, \strlen($this->string) - \strlen($suffix));
+        return $suffix === $grapheme;
     }
 
     public function equalsTo(string|iterable|AbstractString $string): bool
@@ -355,11 +357,13 @@ public function startsWith(string|iterable|AbstractString $prefix): bool
             return false;
         }
 
+        $grapheme = grapheme_extract($this->string, \strlen($prefix), \GRAPHEME_EXTR_MAXBYTES) ?: '';
+
         if ($this->ignoreCase) {
-            return 0 === mb_stripos(grapheme_extract($this->string, \strlen($prefix), \GRAPHEME_EXTR_MAXBYTES), $prefix, 0, 'UTF-8');
+            return 0 === mb_stripos($grapheme, $prefix, 0, 'UTF-8');
         }
 
-        return $prefix === grapheme_extract($this->string, \strlen($prefix), \GRAPHEME_EXTR_MAXBYTES);
+        return $prefix === $grapheme;
     }
 
     public function __wakeup(): void