#2395 - Handle empty output for redpen

autoload/ale/handlers/redpen.vim

@@ -4,10 +4,10 @@
 function! ale#handlers#redpen#HandleRedpenOutput(buffer, lines) abort
     " Only one file was passed to redpen. So response array has only one
     " element.
-    let l:res = json_decode(join(a:lines))[0]
+    let l:res = get(ale#util#FuzzyJSONDecode(a:lines, []), 0, {})
     let l:output = []
 
-    for l:err in l:res.errors
+    for l:err in get(l:res, 'errors', [])
         let l:item = {
         \   'text': l:err.message,
         \   'type': 'W',

test/command_callback/test_psalm_command_callbacks.vader

@@ -24,6 +24,9 @@ Execute(Vendor executables should be detected):
 
 Execute(The project path should be correct for .git directories):
   call ale#test#SetFilename('psalm-project/test.php')
+
+  if !isdirectory(g:dir . '/.git')
     call mkdir(g:dir . '/.git')
+  endif
 
   AssertLSPProject g:dir

test/handler/test_redpen_handler.vader

@@ -80,7 +80,7 @@ Execute(redpen handler should handle errors output):
   \   ']',
   \ ])
 
-Execute(redpen handler should no error output):
+Execute(The redpen handler should handle an empty error list):
   AssertEqual
   \ [],
   \ ale#handlers#redpen#HandleRedpenOutput(bufnr(''), [
@@ -91,3 +91,8 @@ Execute(redpen handler should no error output):
   \   '  }',
   \   ']',
   \ ])
+
+Execute(The redpen handler should handle totally empty output):
+  AssertEqual
+  \ [],
+  \ ale#handlers#redpen#HandleRedpenOutput(bufnr(''), [])