Different source code print when there are no columns

I recently merged !372 (merged) which added a print out of the source code where the error occurred in the error message.

That looks something like this:

./Extern.sac:14:9 abort:
  13. int main() {
  14.     c = pow2(10);
              ↑
  15.     p("Hello, world!");
  16.     c = pow2(c);

However, after having used the new version with this feature for a bit I noticed that often the compiler actually does not have the column where the error happened. In that case the source code print out looks like this:

./Extern.sac:14: abort:
  13. int main() {
  14.     c = pow2(10);
     ↑
  15.     p("Hello, world!");
  16.     c = pow2(c);

With this issue I want to suggest to print something different with the arrow when the compiler only has the line number. Here are my ideas so far:

Underline the whole line with ^ symbols.

./Extern.sac:14: abort:
  13. int main() {
  14.     c = pow2(10);
      ^^^^^^^^^^^^^^^^^
  15.     p("Hello, world!");
  16.     c = pow2(c);

Underline the whole line with ^ symbols but skip leading white space.

./Extern.sac:14: abort:
  13. int main() {
  14.     c = pow2(10);
          ^^^^^^^^^^^^^
  15.     p("Hello, world!");
  16.     c = pow2(c);

Right arrow at the start of the line.

./Extern.sac:14: abort:
   13. int main() {
 → 14.     c = pow2(10); 
   15.     p("Hello, world!");
   16.     c = pow2(c);

Right arrow at the start of the line behind the line number.

./Extern.sac:14: abort:
  13.  int main() {
  14. →    c = pow2(10); 
  15.      p("Hello, world!");
  16.      c = pow2(c);

Left arrow plus space at the end of the line:

./Extern.sac:14: abort:
  13. int main() {
  14.     c = pow2(10); ←
  15.     p("Hello, world!");
  16.     c = pow2(c);

Combine left arrow before line number and ^ under line skipping white space on the left

./Extern.sac:14: abort:
   13. int main() {
 → 14.     c = pow2(10); 
           ^^^^^^^^^^^^^
   15.     p("Hello, world!");
   16.     c = pow2(c);

---

I like Right arrow at the start of the line. or Combine left arrow before line number and ^ under line skipping white space on the left the most. I would love to hear some of your opinions and ideas.