How about:
```python

except TypeError as e:
    raise TypeError('A coordinate type on the collapsing dimension'
                    ' cannot be collapsed ({}).'.format(e.message))
```
I think this is a little more readable and keeps the line length under 80 chars in keeping with PEP8. If you'd like to keep the comment, add an extra space before it (two blank spaces are required before an inline comment). You might want to consider putting the comment above the try to give yourself more room. With regards to your comment, I'm not sure if the units are actually considered, I suspect it's just the dtype of the coordinate values.