Vala scanner goes into loop and may crash with certain code

### What Happened?

Inserted some code in the form:
```
try {
---
---
} catch () {
---
---
}
```

into a Vala file. On opening the symbol outline it remained blank and inspecting the terminal output indicated it had gone into a loop. Repeated Terminal warning: `vala_scanner_read_token: assertion 'self != NULL' failed`

Editing the file with "autosave" on resulted in random crashes which back traced to the outline plugin.

### Steps to Reproduce

1. Edit some code containing lines in the form mentioned above with the outline plugin on

### Expected Behavior

The outline plugin should handle invalid Vala code without crashing or going into a loop.

### OS Version

7.x (Horus)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

_No response_