#1524 Do not try to check buffers with empty filetypes

autoload/ale.vim

@@ -60,23 +60,31 @@ function! ale#ShouldDoNothing(buffer) abort
         return 1
     endif
 
-    " Do nothing for blacklisted files
-    if index(get(g:, 'ale_filetype_blacklist', []), getbufvar(a:buffer, '&filetype')) >= 0
+    let l:filetype = getbufvar(a:buffer, '&filetype')
+
+    " Do nothing when there's no filetype.
+    if l:filetype is# ''
         return 1
     endif
 
-    " Do nothing if running from command mode
+    " Do nothing for blacklisted files.
+    if index(get(g:, 'ale_filetype_blacklist', []), l:filetype) >= 0
+        return 1
+    endif
+
+    " Do nothing if running from command mode.
     if s:getcmdwintype_exists && !empty(getcmdwintype())
         return 1
     endif
 
     let l:filename = fnamemodify(bufname(a:buffer), ':t')
 
+    " Do nothing for directories.
     if l:filename is# '.'
         return 1
     endif
 
-    " Do nothing if running in the sandbox
+    " Do nothing if running in the sandbox.
     if ale#util#InSandbox()
         return 1
     endif

autoload/ale/engine.vim

@@ -98,11 +98,13 @@ endfunction
 " Register a temporary file to be managed with the ALE engine for
 " a current job run.
 function! ale#engine#ManageFile(buffer, filename) abort
+    call ale#engine#InitBufferInfo(a:buffer)
     call add(g:ale_buffer_info[a:buffer].temporary_file_list, a:filename)
 endfunction
 
 " Same as the above, but manage an entire directory.
 function! ale#engine#ManageDirectory(buffer, directory) abort
+    call ale#engine#InitBufferInfo(a:buffer)
     call add(g:ale_buffer_info[a:buffer].temporary_directory_list, a:directory)
 endfunction