Strange behaviour when components lack a closing </script> tag

[snoopdouglas]

Version

15.3.0

Reproduction link

https://codesandbox.io/s/l7m0o5kwlq

Steps to reproduce

• Create a component with an opening <script> tag, but without a closing </script> one.
• Add a prop to that component, eg msg.
• Mount that component with msg set.

What is expected?

I'd expect to see an error in compilation, eg. "no closing script tag".

What is actually happening?

No error is thrown, and props fail to register, causing a runtime error that the prop is not defined on the component, eg.:

Property or method "msg" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties

[geri777]

Same here. It seems that the script part is ignored by Vue loader at all, if there is no closing tag.

[gustojs]

Bumping this up. Just today there were two cases on the chat where people couldn't find out why their templates and Vue-Devtools don't see any data or computed and the reason was a missing closing </script> tag.

A warning of some sort could come handy.

[IS-Kuan]

I strongly think this issue should be fixed. I just debugged for 40 minutes until noticed that I lost a </script> closing tag, while vue-cli-service doesn't output any error at all.

This issue still exists in v15.8.3.