Haml checker throws big error message when the buffer is fine.

[ar1a]

• What you did, and what you expected to happen instead
  https://ptpb.pw/Ne6U.png
  I don't expect a massive error there
• Whether and how you were able to [reproduce the issue in emacs -Q][emacsQ]
  Steps:

• Install flycheck and haml-mode
• make sure haml is installed (gem install haml)
• create a haml file (make sure haml-mode is the current major mode)
• fill it with something, for example I used

%h1 Hello
%aas
  %wew

• observe error

• Your Flycheck setup from M-x flycheck-verify-setup

Syntax checkers for buffer test.html.haml in haml-mode:

  haml
    - may enable: yes
    - executable: Found at /usr/bin/haml

Flycheck Mode is enabled.  Use C-u C-c ! x to enable disabled
checkers.

--------------------

Flycheck version: 30
Emacs version:    25.3.1
System:           x86_64-pc-linux-gnu
Window system:    x

• Your operating system
  Arch Linux

[cpitclaudel]

Thanks. Is this actually related to flycheck ? It looks like a bug in haml to me. Can you try C-c ! C-v to see the command line invocation used by flycheck, and then run than in a terminal to compare ?

[ar1a]

C-c ! C-v isn't bound to anything

[ar1a]

Googled and found #852 i presume you meant C-c ! C-c.

It ran the command
haml -c --stdin < /tmp/test.html.haml
and when i run it, the output is

Exception on line 341: no implicit conversion of nil into String
  Use --trace for backtrace.

So I would suppose this could be a haml error?

Although, when i try without --stdin and run
haml -c /tmp/test.html.haml

I get returned

Syntax OK

EDIT: Well I've been experiencing this for a while but it looks like haml/haml#958 just got merged, so I have to wait for the next release.