Nullish dynamic event name with a modifier creates attribute with modifier's name

[markrian]

Vue version

3.5.13

Link to minimal reproduction

https://codepen.io/markrian/pen/OPJmmoW

Steps to reproduce

1. Write a dynamic event binding with a modifier, e.g., @[eventName].once="onEvent".
2. Set eventName to an empty value, like null, undefined or empty string.
3. Notice that the modifier name is written as an attribute on the element.

For example:

What is expected?

The modifier name should not become an attribute on the element.

What is actually happening?

The modifier name becomes an attribute on the element, e.g.,

System Info

Any additional comments?

Vue 2.7.16 behaves as expected, i.e., does not create an attribute.