fix(tree): Keep panic infos consistent when wildcard type build faild

[kingcanfish]

fix(tree): Keep panic infos consistent when wildcard type build faild

When I run the demo1

// demo1
func main() {
	router := gin.Default()
	router.GET("/abc/bar", nil)
	router.GET("/abc/x*z", nil)

	router.Run("localhost:8080")
}

it got the panic:panic: no / before catch-all in path '/abc/x*z'

but when i run the demo2

// demo2
func main() {
	router := gin.Default()
	router.GET("/abc/bar", nil)
	router.GET("/abc/b*r", nil)

	router.Run("localhost:8080")
} 

it got the panic: panic: runtime error: index out of range [-1] Although the end result is the same(panic), the different panic informations may cause some confusion.

So, add the i < 0 condition to keep the panic infos same