add healthcheck

lua/luasnip/health.lua

@@ -0,0 +1,14 @@
+return {
+	check = function()
+		vim.health.start("luasnip")
+		local jsregexp = require("luasnip.util.jsregexp")
+		if jsregexp then
+			vim.health.ok("jsregexp is installed")
+		else
+			vim.health.error([[
+            For Variable/Placeholder-transformations, luasnip requires
+            the jsregexp library. See `:h luasnip-transformations` for advice
+        ]])
+		end
+	end,
+}