From 0d435423d12e61c0d14adb6d04396c08a6a650f1 Mon Sep 17 00:00:00 2001
From: Yuki Yamamoto <yymmt3.waste@gmail.com>
Date: Fri, 6 Dec 2019 00:14:54 +0900
Subject: [PATCH] Add guard to handle index out of range exception (#83)

---
 Sources/SwiftJWT/JWTDecoder.swift | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Sources/SwiftJWT/JWTDecoder.swift b/Sources/SwiftJWT/JWTDecoder.swift
index 40350f3..d855204 100644
--- a/Sources/SwiftJWT/JWTDecoder.swift
+++ b/Sources/SwiftJWT/JWTDecoder.swift
@@ -75,7 +75,8 @@ public class JWTDecoder: BodyDecoder {
     public func decode<T : Decodable>(_ type: T.Type, fromString: String) throws -> T {
         // Seperate the JWT into the headers and claims.
         let components = fromString.components(separatedBy: ".")
-        guard let headerData = JWTDecoder.data(base64urlEncoded: components[0]),
+        guard components.count > 1,
+         let headerData = JWTDecoder.data(base64urlEncoded: components[0]),
             let claimsData = JWTDecoder.data(base64urlEncoded: components[1])
         else {
             throw JWTError.invalidJWTString