Remove superfluous checks for empty realnames

ftp)

src/MD_STD.php

@@ -44,7 +44,7 @@ final class MD_STD {
     public static function realpath(string $path):string {
 
         $output = \realpath($path);
-        if (!\is_string($output) || empty($output)) {
+        if (!\is_string($output)) {
             throw new MDFileDoesNotExist("The file {$path} does not exist or is not readable.");
         }
         return $output;

src/MD_STD_IN.php

@@ -202,6 +202,11 @@ final class MD_STD_IN {
             throw new MDInvalidUrl("Invalid input URL");
         }
 
+        // Check for valid schemes
+        if (MD_STD::startsWithAny($input, ['https://', 'http://', 'ftp://']) === false) {
+            throw new MDInvalidUrl("Invalid input URL");
+        }
+
         return $output;
 
     }

src/MD_STD_SEC.php

@@ -134,8 +134,8 @@ final class MD_STD_SEC {
     /**
      * Send CSP headers.
      *
-     * @param array{default-src: string, connect-src: string, script-src: string, img-src: string, media-src: string, style-src: string, frame-src: string, object-src: string, base-uri: string, form-action: string, frame-ancestors?: string} $directives      Directives to send. Font source is always set to 'self', and hence excluded.
-     * @param string                                                                                                                                                                                                                             $frame_ancestors Frame ancestors directive. Default is to not set it.
+     * @param array{default-src: string, connect-src: string, script-src: string, img-src: string, media-src: string, style-src: string, frame-src: string, object-src: string, base-uri: string, form-action: string, worker-src?: string, frame-ancestors?: string} $directives      Directives to send. Font source is always set to 'self', and hence excluded.
+     * @param string                                                                                                                                                                                                                                                  $frame_ancestors Frame ancestors directive. Default is to not set it.
      *
      * @return void
      */