Add getOrFail() shorthand to ParseResult for explicit strict key access

get(\$key, true) works but requires reading the boolean argument at
every call site to understand its intent. getOrFail() expresses the
strict contract directly in its name and returns a non-nullable string,
giving callers a cleaner type signature without requiring an assertion
or null-coalesce at the call site.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: aymanrb

src/ParseResult.php

@@ -66,6 +66,15 @@ public function get(string $resultDataKey, bool $failOnUndefinedKey = false): ?s
         return $this->parsedRawData[$resultDataKey];
     }
 
+    public function getOrFail(string $resultDataKey): string
+    {
+        if (!$this->keyExists($resultDataKey)) {
+            throw new InvalidParsedDataKeyException('Undefined results key: ' . $resultDataKey);
+        }
+
+        return $this->parsedRawData[$resultDataKey];
+    }
+
     private function cleanData(): void
     {
         $this->parsedRawData = array_map($this->cleanElement(...), $this->parsedRawData);