Report exceptions thrown for stylelint

autoload/ale/handlers/css.vim

@@ -37,6 +37,18 @@ function! ale#handlers#css#HandleCSSLintFormat(buffer, lines) abort
 endfunction
 
 function! ale#handlers#css#HandleStyleLintFormat(buffer, lines) abort
+    let l:exception_pattern = '\v^Error:'
+
+    for l:line in a:lines[:10]
+        if len(matchlist(l:line, l:exception_pattern)) > 0
+            return [{
+            \   'lnum': 1,
+            \   'text': 'stylelint exception thrown (type :ALEDetail for more information)',
+            \   'detail': join(a:lines, "\n"),
+            \}]
+        endif
+    endfor
+
     " Matches patterns line the following:
     "
     " src/main.css

test/handler/test_stylelint_handler.vader

@@ -1,3 +1,6 @@
+After:
+  unlet! g:error_lines
+
 Execute (stylelint errors should be handled correctly):
   " Stylelint includes trailing spaces for output. This needs to be taken into
   " account for parsing errors.
@@ -21,3 +24,18 @@ Execute (stylelint errors should be handled correctly):
   \   ' 108:10  ✖  Unexpected leading zero         number-leading-zero                 ',
   \   ' 116:20  ✖  Expected a trailing semicolon   declaration-block-trailing-semicolon',
   \ ])
+
+Execute (stylelint should complain when no configuration file is used):
+  let g:error_lines = [
+  \ 'Error: No configuration provided for /home/w0rp/.vim/bundle/ale/test.stylus',
+  \ '    at module.exports (/home/w0rp/.vim/bundle/ale/node_modules/stylelint/lib/utils/configurationError.js:8:27)',
+  \ '    at stylelint._fullExplorer.load.then.then.config (/home/w0rp/.vim/bundle/ale/node_modules/stylelint/lib/getConfigForFile.js:39:13)',
+  \]
+
+  AssertEqual
+  \ [{
+  \   'lnum': 1,
+  \   'text': 'stylelint exception thrown (type :ALEDetail for more information)',
+  \   'detail': join(g:error_lines, "\n"),
+  \ }],
+  \ ale#handlers#css#HandleStyleLintFormat(347, g:error_lines[:])