What steps will reproduce the problem?
1. Become host
2. Share multiple files (select at least 2, right click and press Share)
3. Close multiple shared files (select at least 2 from File List, right click 
and press Stop Sharing)

*** Update to latest code for the ability to close multiple files at the same 
time

What is the expected output? What do you see instead?
Expected: Close_Shared_File feu sent to other clients
Getting: Close_Shared_File feu, but also a Null pointer at server (See code)

Please use labels and text to provide additional information.

============ Eclipse ===============

Received: FEU: NF | Type: Connection_Succeed | ASGN ID: 0

GetUpdate: FEU: NF | Type: Connection_Succeed | ASGN ID: 0
Sent: FEU: NF | Type: User_Connected | UID: 0 | UNAME: Ryan

Received: FEU: NF | Type: User_Connected | UID: 0 | UNAME: Ryan

Received: FEU: NF | Type: User_Connected | UID: 0 | UNAME: Ryan

Received: FEU: NF | Type: New_Host | UID: -1 | FID: -1 | CONTENT:  | 

GetUpdate: FEU: NF | Type: User_Connected | UID: 0 | UNAME: Ryan
GetUpdate: FEU: NF | Type: User_Connected | UID: 0 | UNAME: Ryan
GetUpdate: FEU: NF | Type: New_Host | UID: -1 | FID: -1 | CONTENT:  | 
Sent: FEU: NF | Type: Request_Host | UID: 0 | FID: -1 | CONTENT: Ryan | 

Received: FEU: NF | Type: New_Host | UID: 0 | FID: -1 | CONTENT:  | 

GetUpdate: FEU: NF | Type: New_Host | UID: 0 | FID: -1 | CONTENT:  | 
Sent: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 0 | CONTENT: Test.txt | 

Received: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 0 | CONTENT: Test.txt 
| 

GetUpdate: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 0 | CONTENT: 
Test.txt | 
Sent: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 1 | CONTENT: Test2.txt | 

Received: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 1 | CONTENT: 
Test2.txt | 

GetUpdate: FEU: NF | Type: New_Shared_File | UID: 0 | FID: 1 | CONTENT: 
Test2.txt | 
*** Closing shared file: 0 - Test.txt
*** Closing shared file: 1 - Test2.txt
Sent: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: Test.txt | 

Sent: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 1 | CONTENT: Test2.txt 
| 

Received: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: 
Test.txt | 

GetUpdate: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: 
Test.txt | 
Received: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 1 | CONTENT: 
Test2.txt | 

GetUpdate: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 1 | CONTENT: 
Test2.txt | 
Sent: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: Test.txt | 

Received: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: 
Test.txt | 

GetUpdate: FEU: NF | Type: Close_Shared_File | UID: 0 | FID: 0 | CONTENT: 
Test.txt | 

============== Server ===================

Server Running.
Accepted Client
Sent client UID: 0
Client Added
Sending: --------------------
Notification FEU:
type: Connection_Succeed
assign id: 0
---------------------
Received: --------------------
Notification FEU:
type: User_Connected
user id: 0
username: Ryan
---------------------
Sending 1 users to client 0
Sending: --------------------
Notification FEU:
type: User_Connected
user id: 0
username: Ryan
---------------------
Sending: --------------------
Notification FEU:
type: User_Connected
user id: 0
username: Ryan
---------------------
Sending: --------------------
Notification FEU:
type: New_Host
---------------------
Received: --------------------
Notification FEU:
type: Request_Host
---------------------
Sending: --------------------
Notification FEU:
type: New_Host
---------------------
Received: --------------------
Notification FEU:
type: New_Shared_File
---------------------
Sending: --------------------
Notification FEU:
type: New_Shared_File
---------------------
Added a new file. FID: 0
Sending: --------------------
Notification FEU:
type: New_Shared_File
---------------------
Received: --------------------
Notification FEU:
type: New_Shared_File
---------------------
Added a new file. FID: 1
Received: --------------------
Notification FEU:
type: Close_Shared_File
---------------------
Received: --------------------
Notification FEU:
type: Close_Shared_File
---------------------
Removed file 0
Sending: --------------------
Notification FEU:
type: Close_Shared_File
---------------------
Removed file 1
Sending: --------------------
Notification FEU:
type: Close_Shared_File
---------------------
Received: --------------------
Notification FEU:
type: Close_Shared_File
---------------------
Exception in thread "Thread-2" java.lang.NullPointerException
    at FileUserManager.removeFile(FileUserManager.java:216)
    at NotificationProcessor.processFEU(NotificationProcessor.java:71)
    at NotificationProcessor.run(NotificationProcessor.java:29)
    at java.lang.Thread.run(Thread.java:680)
Sending: --------------------
Notification FEU:
type: Close_Shared_File
---------------------