Better user error when passing a config file with a dash in the filename (which fails)

[eatonphil]

Description

chalk load doesn't support a config filename with a dash in it. It doesn't need to support that, but the error is opaque. Chalk should at least tell the user that the issue is because there's a dash in the filename.

admin@ubuntu:~$ ./chalk load heartbeat-config.c4m
warn:  Could not find or install cosign; cannot sign or verify.
info:  Attempting to load module from: heartbeat-config.c4m


 Configuring Component: /home/admin/heartbeat-config
 Finished configuration for /home/admin/heartbeat-config
info:  [testing config]: Validating configuration.
error: chalk: [testing config]: 2:5:
Parse error: Expected either end of statement or: TtFrom
  use heartbeat-config from "/home/admin"
      ^
admin@ubuntu:~$ mv heartbeat-config.c4m heartbeat_config.c4m
admin@ubuntu:~$ ./chalk load heartbeat_config.c4m
warn:  Could not find or install cosign; cannot sign or verify.
info:  Attempting to load module from: heartbeat_config.c4m

 Configuring Component: /home/admin/heartbeat_config
 Finished configuration for /home/admin/heartbeat_config
info:  [testing config]: Validating configuration.
info:  [testing config]: Configuration successfully validated.
info:  Configuration replaced in binary: /home/admin/chalk
info:  /home/admin/.local/chalk/chalk.log: Open (sink conf='default_out')
info:  Full chalk report appended to: ~/.local/chalk/chalk.log

Result

Instead it should do something like this:

admin@ubuntu:~$ ./chalk load heartbeat-config.c4m
error: c4m config file name must not contain dash