Massively reduce the amount of code needed for linter tests

ale_linters/go/gotype.vim

@@ -3,10 +3,9 @@
 
 function! ale_linters#go#gotype#GetCommand(buffer) abort
     if expand('#' . a:buffer . ':p') =~# '_test\.go$'
-        return
+        return ''
     endif
 
-
     return ale#path#BufferCdString(a:buffer) . ' gotype .'
 endfunction