[L016] Applying rule L016 threw an Exception: tuple index out of range 


No errors during `sqlfluff parse` only error during `lint` and `fix`
I do not have a sql script that I can share (hopefully I can create a script that i can share). However the detail is as follows:

- Had CTE (with blocks and alias)
- Long sql statements (select, where, order by, etc.)
- Sql selected one column per line


## Expected Behaviour
`L:  1 | P: 177 | L016 | Line is too long`
## Observed Behaviour
Error 

```python
CRITICAL   [L016] Applying rule L016 threw an Exception: tuple index out of range 
Traceback (most recent call last):
  File "/Users/<username>/.local/pipx/venvs/sqlfluff/lib/python3.9/site-packages/sqlfluff/core/rules/base.py", line 290, in crawl
    res = self._eval(
  File "/Users/<username>/.local/pipx/venvs/sqlfluff/lib/python3.9/site-packages/sqlfluff/core/rules/std/L016.py", line 437, in _eval
    fixes = self._eval_line_for_breaks(this_line)
  File "/Users/<username>/.local/pipx/venvs/sqlfluff/lib/python3.9/site-packages/sqlfluff/core/rules/std/L016.py", line 274, in _eval_line_for_breaks
    self.logger.info("    {0}: {1!r}".format(idx, sec))
  File "/Users/<username>/.local/pipx/venvs/sqlfluff/lib/python3.9/site-packages/sqlfluff/core/rules/std/L016.py", line 56, in __repr__
    pos=self.segments[0].get_start_pos_marker(),
IndexError: tuple index out of range
== [views/v_gre_susp.sql] FAIL
```

`L:  1 | P: 177 | L016 | Unexpected exception: tuple index out of range; Could you open an issue at https://github.com/sqlfluff/sqlfluff/issues ? You can  ignore this exception for now, by adding '--noqa: L016' at the end of line 15`
## Steps to Reproduce

## Version
sqlfluff, version 0.5.0

## Configuration
```
No custom configuration. Running out of the box with ansi dialect
```

diff --git a/src/sqlfluff/core/rules/std/L016.py b/src/sqlfluff/core/rules/std/L016.py
index f1e7b762..98cfa4b5 100644
--- a/src/sqlfluff/core/rules/std/L016.py
+++ b/src/sqlfluff/core/rules/std/L016.py
@@ -53,7 +53,9 @@ class Rule_L016(Rule_L003):
                     indent_balance=self.indent_balance,
                     indent_impulse=self.indent_impulse,
                     segments="".join(elem.raw for elem in self.segments),
-                    pos=self.segments[0].get_start_pos_marker(),
+                    pos=self.segments[0].get_start_pos_marker()
+                    if self.segments
+                    else "",
                 )
 
             @property
@@ -334,9 +336,10 @@ class Rule_L016(Rule_L003):
 
         fixes = []
         for split, indent in split_at:
-            fixes += split.generate_fixes_to_coerce(
-                segments, indent_section, self, indent
-            )
+            if split.segments:
+                fixes += split.generate_fixes_to_coerce(
+                    segments, indent_section, self, indent
+                )
 
         self.logger.info("Fixes: %s", fixes)
 
['src/sqlfluff/core/rules/std/L016.py']