Parse failures can't easily be fixed from the wiki interface

If I have a page in LaTeX format with the following as its entire content:

```
\section{
```

then the page does not load at all, so I'm unable to get at the edit link to fix it.

If I manually insert `_edit/` into the link then I can fix it, but this is hardly ideal. Parse failures should be handled, and either rejected before committing, or displayed in the normal page area until they are fixed (or ideally, both).