LibJS: Make ParserError::to_string infallible

Author: https://github.com/shannonbooth
Commit: 0090b916dd
Pull-request: https://github.com/SerenityOS/serenity/pull/23817
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibJS/ParserError.cpp

@@ -12,11 +12,11 @@
 
 namespace JS {
 
-ErrorOr<String> ParserError::to_string() const
+String ParserError::to_string() const
 {
     if (!position.has_value())
-        return String::from_byte_string(message);
-    return String::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column);
+        return MUST(String::from_byte_string(message));
+    return MUST(String::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column));
 }
 
 ByteString ParserError::to_byte_string() const