Flow checker: bail out if there is no .flowconfig.

plugin/syntastic.vim

@@ -19,7 +19,7 @@ if has('reltime')
     lockvar! g:_SYNTASTIC_START
 endif
 
-let g:_SYNTASTIC_VERSION = '3.6.0-57'
+let g:_SYNTASTIC_VERSION = '3.6.0-58'
 lockvar g:_SYNTASTIC_VERSION
 
 " Sanity checks {{{1

syntax_checkers/javascript/flow.vim

@@ -22,6 +22,10 @@ let s:save_cpo = &cpo
 set cpo&vim
 
 function! SyntaxCheckers_javascript_flow_GetLocList() dict
+    if findfile('.flowconfig', '.;') == ''
+        return []
+    endif
+
     let makeprg = self.makeprgBuild({
         \ 'exe': self.getExecEscaped() . ' check',
         \ 'args_after': '--show-all-errors --json' })