Remove alpha from hexadecimal colors

We don't use those in the UI (and don't even consider them)  but the spec does allow those.

Author: vmcj

webapp/src/Utils/Utils.php

@@ -352,6 +352,12 @@ public static function convertToColor(string $hex): ?string
      */
     public static function parseHexColor(string $hex): array
     {
+        // Ignore alpha in hexstrings
+        if (strlen($hex) === 5) {
+            $hex = substr($hex, 0, 4);
+        } else if (strlen($hex) === 9) {
+            $hex = substr($hex, 0, 7);
+        }
         // Source: https://stackoverflow.com/a/21966100
         $length = (strlen($hex) - 1) / 3;
         $fact = [17, 1, 0.062272][$length - 1];