Types: type narrowing not work in parent component when child component use union type to defineProps

[zjtakato]

Vue version

3.3.4

Link to minimal reproduction

https://play.vuejs.org/#eNqNUk1v1DAQ/SuWLwWpGx/KKYRSQD2UA1SUG+YQ4snWxV+yx9tFZf87Y0e7DemHeoniN/PevPm44x9CaDYZeMu7NEQdkCXAHE6lk07b4COyT96yMdJH8kbQoxIkLxnSDd4lZFv2TvKkxqQmvBOTWJXpEGwwPQK9uiLG8E+AQgADA0rONr3JBaBfUZLEgcGPOSaqMep1c5O8I5930jGyMpARbSB+DajJg+Qtq5ES643xt58rhjHD8R4frmH4/Qh+k7YFk/wyQoK4oe4OMezjGshkCZ9ffYEt/R+C1qtsKPuZ4DdI3uTicUr7mJ0i27O86vaizlq79fd0vkVwad9UMVoydzVfcpp92cFTrd/bPWlOKk+6HU1xv7flopnp3ZpGjyRDo9cOIY79AOzChYyX0Yc0iZedvW/ZkS740dsC1bW1LGEk34RQqXv+VV3uQoD409IfEfjxc5JQMGoHldjNTPydK56+ek3Jz17a8oymY17ZPiwOaQr8P8V64GVb14ghtUIMyhFNgdGb2DhA4YIVZ5QmYnaoLayUt2c08uaNUDrhHG4g2dWv6G/ptEhktvnCr/cWVxGo8Vju4mVlF7R56UXoQfnDVez+AfyVXwE=

Steps to reproduce

If type prop is 'select', value should just a 'String[]', but it allow 'String | String[]'.

In React, it is expected.

What is expected?

Type narrowing should work

What is actually happening?

Type narrowing not work

System Info

No response

Any additional comments?

No response

[pikax]

I believe this is caused by the language service not by vue core

/cc @johnsoncodehk

[davidmatter]

@pikax @johnsoncodehk same as #9336. Fixed in vuejs/language-tools#3672