Don't exit the shell on syntax error

[certik]

C:\Program Files\Git$ cd ~
Error: Failed to execute

Caused by:
     --> 1:4
      |
    1 | cd ~
      |    ^---
      |
      = expected EOI, AND_IF, OR_IF, Stdout, StdoutStderr, cmd_suffix, or separator_op
error: process didn't exit successfully: `target\debug\shell.exe` (exit code: 1)

This exits the shell. Instead show the next prompt.

[certik]

This one is high priority, as for daily use, we do not want to exit the shell if I mistype something or try to use a feature that is not implemented yet.

[prsabahrami]

I am working on adding miette support for pest.
That way this can be easily taken care of.

[prsabahrami]

This has been fixed in #38
Support for miette should be added later. Switching from bug to enhancement.

[certik]

This issue is fixed. I opened a new one (#77) for miette.