fix diagnostic refresh

syntax errors dose not refresh after reload workspace by change config or `Lua.runtime.XXX`

Author: sumneko

script/files.lua

@@ -283,6 +283,9 @@ end
 
 function m.resetText(uri)
     local file = m.fileMap[uri]
+    if not file then
+        return
+    end
     local originText = file.originText
     file.originText = nil
     m.setText(uri, originText, file.trusted)

script/workspace/workspace.lua

@@ -558,7 +558,9 @@ config.watch(function (uri, key, value, oldValue)
     or key:find '^Lua.type'
     or key:find '^files' then
         if value ~= oldValue then
-            m.reload(scope.getScope(uri))
+            local scp = scope.getScope(uri)
+            m.reload(scp)
+            m.resetFiles(scp)
         end
     end
 end)