refactor(accessToken): 코드 추상화 수준 맞추기

- NPE 처리 추가.

Author: m-a-king

src/main/java/com/somemore/auth/jwt/filter/JwtAuthFilter.java

@@ -61,7 +61,7 @@ private EncodedToken getAccessToken(HttpServletRequest request) {
         EncodedToken accessToken = findAccessTokenFromCookie(request);
 
         if (accessToken.isUninitialized()) {
-            accessToken = new EncodedToken(request.getHeader("Authorization"));
+            accessToken = findAccessTokenFromHeader(request);
         }
 
         if (accessToken.isUninitialized()) {
@@ -72,6 +72,15 @@ private EncodedToken getAccessToken(HttpServletRequest request) {
         return accessToken.removePrefix(prefix);
     }
 
+    private static EncodedToken findAccessTokenFromHeader(HttpServletRequest request) {
+        String authorizationHeader = request.getHeader("Authorization");
+        if (authorizationHeader == null || authorizationHeader.isEmpty()) {
+            return new EncodedToken("UNINITIALIZED");
+        }
+
+        return new EncodedToken(authorizationHeader);
+    }
+
     private EncodedToken findAccessTokenFromCookie(HttpServletRequest request) {
         Cookie[] cookies = request.getCookies();
         if (cookies == null) {