main.py: add error shell flag for popping a shell on exceptions

main.py

@@ -2,6 +2,8 @@
 
 import click
 from traceback import format_exc as get_trace
+import subprocess
+
 from logger import logging, setup_logging, verbose_option
 from wrapper import nowrapper_option
 from config import config, config_option, cmd_config
@@ -17,13 +19,15 @@ from ssh import cmd_ssh
 
 
 @click.group()
+@click.option('--error-shell', 'error_shell', is_flag=True, default=False, help='Spawn shell after error occurs')
 @verbose_option
 @config_option
 @nowrapper_option
-def cli(verbose: bool = False, config_file: str = None, no_wrapper: bool = False):
+def cli(verbose: bool = False, config_file: str = None, no_wrapper: bool = False, error_shell: bool = False):
     setup_logging(verbose)
     config.runtime['verbose'] = verbose
     config.runtime['no_wrap'] = no_wrapper
+    config.runtime['error_shell'] = error_shell
     config.try_load_file(config_file)
 
 
@@ -32,6 +36,9 @@ def main():
         return cli(prog_name='kupferbootstrap')
     except Exception:
         logging.fatal(get_trace())
+        logging.info('Starting error shell. Type exit to quit.')
+        if config.runtime['error_shell']:
+            subprocess.call('/bin/bash')
         exit(1)