syntax error in type annotation causes misleading error message

imba version 2.0.0-alpha.205
vscode tooling version 3.1.12

I made a syntax error by leaving out a `"` in a type annotation like this:

```imba
tag Foo
prop fruit\"apple"|"orange = "apple"
```

The error is not highlighted on the line where it happened, other strings much further down my tag show an error.

I tried this in a plain imba file without any tags like this:

```imba
let foo\"a"|"b = "a"
console.log(foo)
```

executing the file didn't report an error but also didn't log anything.

Reproduce the examples in a tag and in a plain Imba file using the reported Imba and VS Code tooling versions. Start with the syntax-error handling and editor diagnostic entry points, then verify that the error is reported at the malformed type annotation and that executing the plain file reports the syntax error instead of silently producing no output.

Written by the indexing model from the issue text.