suppress "unknown field" for generated symbols

src/fennel-ls/lint.fnl

@@ -62,6 +62,7 @@ the `file.diagnostics` field, filling it with diagnostics."
   (let [opts {}
         item (analyzer.search-ast server file ?ast stack opts)]
     (if (and (not item)
+             (file.lexical symbol)
              (not (in-or? file.calls symbol))
              ;; this doesn't necessarily have to come thru require; it works
              ;; for built-in modules too