make dep only require nvim 0.8, and make the lazy utils better

lua/dep.lua

@@ -38,7 +38,7 @@ function M.registertree(speclist, overrides)
 
     -- if erroring print out the spec and the error
     if not ok then
-      error(string.format("%s (spec=%s)", err, vim.inspect(spec)))
+      error(string.format("(spec=%s)", vim.inspect(spec)))
     end
   end
 end
@@ -226,7 +226,7 @@ return function(opts)
       local fullpath = vim.api.nvim_call_function(
         'fnamemodify', { fname, ':p' })
       w:start(fullpath, {}, vim.schedule_wrap(function(...)
-        vim.api.nvim_command('checktime')
+        vim.cmd('checktime')
         w:stop()
         watch_file(fname)
       end))