merging the pull request

autoload/sw/server.vim

@@ -149,13 +149,22 @@ endfunction
 function! s:start_sqlwb(type)
     let vid = substitute(v:servername, '\v\/', '-', 'g') . sw#generate_unique_id()
     let cmd = [g:sw_exe, '-feedback=true', '-showProgress=false', '-showTiming=true', '-nosettings', '-variable=vid=' . vid]
+
+    let valid_exe = 1
+    if !filereadable(g:sw_exe)
+        echom g:sw_exe . " is not readable. Make sure the setting g:sw_exe is set and the file exists."
+        let valid_exe = 0
+    endif
+    if match(getfperm(g:sw_exe), "r.x.*") ==# -1
+        echom g:sw_exe . " is not executable. Make sure the permissions are set correctly."
+        let valid_exe = 0
+    endif
+
+    if !valid_exe
+        return
+    endif
+
     if !s:nvim
-        if !filereadable(g:sw_exe)
-            echom g:sw_exe . " is not readable. Make sure the setting g:sw_exe is set and the file exists."
-        endif
-        if match(getfperm(g:sw_exe), "r.x.*") ==# -1
-            echom g:sw_exe . " is not executable. Make sure the permissions are set correctly."
-        endif
         let job = job_start(cmd, {'in_mode': 'raw', 'out_mode': 'raw'})
         let pid = substitute(job, '\v^process ([0-9]+).*$', '\1', 'g')
         let pid = ''
@@ -250,6 +259,9 @@ function! sw#server#disconnect_buffer(...)
     if a:0
         let channel = a:1
     endif
+    if channel == ''
+        return
+    endif
     if (!s:nvim && ch_status(channel) == 'open') || s:nvim
         try
             call sw#server#execute_sql('exit', channel)