I'm getting a similar error that was reported in January. My dump is slightly different so I want to report it. I couldn't figure out how to update the other thread. Sorry...Full file is attached.
Process: SophosAVAgent [1913]
Path: /Library/Sophos Anti-Virus/SophosAntiVirus.app/Contents/MacOS/SophosAVAgent
Identifier: SophosAVAgent
Version: ???
Code Type: X86 (Native)
Parent Process: SophosAntiVirus [1297]
Responsible: SophosAntiVirus [1297]
User ID: 0
Date/Time: 2015-04-23 11:46:42.199 -0400
OS Version: Mac OS X 10.10.3 (14D136)
Report Version: 11
Anonymous UUID: DE1E9EE0-91DD-D1C5-BF16-E81F0447A4EC
Sleep/Wake UUID: 0001EC01-0D12-4821-A4A4-A708148C4F1A
Time Awake Since Boot: 27000 seconds
Time Since Wake: 13000 seconds
Crashed Thread: 15
Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSFileManager fileSystemRepresentationWithPath:]: nil or empty path argument'
Application Specific Backtrace 1:
0 CoreFoundation 0x9058fc63 __raiseError + 195
1 libobjc.A.dylib 0x9b50aa2a objc_exception_throw + 276
2 CoreFoundation 0x9058fb7d +[NSException raise:format:] + 141
3 Foundation 0x933d3dfb -[NSFileManager fileSystemRepresentationWithPath:] + 125
4 Foundation 0x933d3d68 -[NSString(NSPathUtilities) fileSystemRepresentation] + 63
5 SophosAVAgent 0x00005251 -[AdHocScanExecutor scanJob:] + 284
6 SophosAVAgent 0x00003e39 -[ScanChild(BackgroundScanning) backgroundScanWorker] + 680
7 Foundation 0x9340baed -[NSThread main] + 45
8 Foundation 0x9340b896 __NSThread__main__ + 1538
9 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
10 libsystem_pthread.dylib 0x920f3d89 _pthread_body + 0
11 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 0:: Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x994ff9ce mach_msg_trap + 10
1 libsystem_kernel.dylib 0x994fea70 mach_msg + 68
2 com.apple.CoreFoundation 0x9048cef6 __CFRunLoopServiceMachPort + 214
3 com.apple.CoreFoundation 0x9048c309 __CFRunLoopRun + 1529
4 com.apple.CoreFoundation 0x9048baa6 CFRunLoopRunSpecific + 390
5 com.apple.CoreFoundation 0x9048b90b CFRunLoopRunInMode + 123
6 com.apple.Foundation 0x9346334a -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 305
7 com.apple.Foundation 0x93483eff -[NSRunLoop(NSRunLoop) runUntilDate:] + 105
8 SophosAVAgent 0x000029d4 doWork + 385
9 SophosAVAgent 0x00002839 main + 67
10 SophosAVAgent 0x000027ed start + 53
Thread 1:: Dispatch queue: com.apple.libdispatch-manager
0 libsystem_kernel.dylib 0x995068ce kevent64 + 10
1 libdispatch.dylib 0x9943173f _dispatch_mgr_invoke + 245
2 libdispatch.dylib 0x994313a2 _dispatch_mgr_thread + 52
Thread 2:
0 libsystem_kernel.dylib 0x99505512 __psynch_cvwait + 10
1 libsystem_pthread.dylib 0x920f4abe _pthread_cond_wait + 842
2 libsystem_pthread.dylib 0x920f4ce1 pthread_cond_timedwait_relative_np + 47
3 com.apple.Foundation 0x934241e6 -[NSCondition waitUntilDate:] + 403
4 com.apple.Foundation 0x9342400e -[NSConditionLock lockWhenCondition:beforeDate:] + 284
5 SophosAVAgent 0x0000575e -[IPCConnection(PrivateMethods) dataOutputThread] + 168
6 com.apple.Foundation 0x9340baed -[NSThread main] + 45
7 com.apple.Foundation 0x9340b896 __NSThread__main__ + 1538
8 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
9 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
10 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 3:
0 libsystem_kernel.dylib 0x99506dd6 __read + 10
1 com.sophos.sav.savi 0xc00019f3 VENG_read + 67
2 com.sophos.sav.savi 0xc0100da2 HOST_STREAM_ReadStream + 1202
3 com.sophos.sav.savi 0xc00fef9c HNDL_STREAM_ReadStream + 220
4 com.sophos.sav.savi 0xc0005ea3 CLEX_Classify + 819
5 com.sophos.sav.savi 0xc01541f7 RecurseInStream + 10343
6 com.sophos.sav.savi 0xc01596b1 VEEX_SweepStream + 273
7 com.sophos.sav.savi 0xc014fd3a VEEX4_SweepStreamWithPUA + 138
8 com.sophos.sav.savi 0xc02e2f94 sweepThing + 1876
9 com.sophos.sav.savi 0xc02df400 CIScanner_SweepFile + 336
10 com.sophos.sav.savi 0xc01d7c3f CISavi2_SweepFile + 271
11 com.sophos.sum.scan.kit 0x0002276d -[SUMSAVIAdaptor scanFile:error:] + 67
12 com.sophos.sum.scan.kit 0x00022650 -[SUMSAVIAdaptor scanInfo:withExecutor:] + 74
13 com.sophos.sum.scan.kit 0x000280bf -[SUMScanningSweepWalker scanFile:] + 613
14 com.sophos.sum.scan.kit 0x0002062e sweepWalkerScanCallback + 101
15 com.sophos.sav.savi 0xc02fb9f7 sophosRecursiveWalk + 3975
16 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
17 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
18 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
19 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
20 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
21 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
22 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
23 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
24 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
25 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
26 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
27 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
28 com.sophos.sav.savi 0xc02faa0c sophosWalk + 460
29 com.sophos.sum.scan.kit 0x0001fdfb -[SUMSweepWalker walkScanItem:withExecutor:] + 297
30 com.sophos.sum.scan.kit 0x00027e27 -[SUMScanningSweepWalker walkScanItem:withExecutor:] + 176
31 com.sophos.sum.scan.kit 0x0002a6e4 -[SUMScanExecutor(PrivateMethods) lookForThreats] + 394
32 com.sophos.sum.scan.kit 0x0002a127 -[SUMScanExecutor(PrivateMethods) executeScan] + 607
33 com.sophos.sum.scan.kit 0x00029a8a -[SUMScanExecutor start] + 113
34 com.apple.Foundation 0x9340baed -[NSThread main] + 45
35 com.apple.Foundation 0x9340b896 __NSThread__main__ + 1538
36 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
37 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
38 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 4:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 5:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 6:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 7:
0 libsystem_kernel.dylib 0x99507252 stat + 10
1 com.sophos.sav.savi 0xc00025c4 MACV_isMacFile + 212
2 com.sophos.sav.savi 0xc006c1c1 Detect_MAC + 129
3 com.sophos.sav.savi 0xc000400b CLALG_Execute + 107
4 com.sophos.sav.savi 0xc0003734 ALGE_CLMETH_Classify + 756
5 com.sophos.sav.savi 0xc0005f7b CLEX_Classify + 1035
6 com.sophos.sav.savi 0xc01541f7 RecurseInStream + 10343
7 com.sophos.sav.savi 0xc01596b1 VEEX_SweepStream + 273
8 com.sophos.sav.savi 0xc014fd3a VEEX4_SweepStreamWithPUA + 138
9 com.sophos.sav.savi 0xc02e2f94 sweepThing + 1876
10 com.sophos.sav.savi 0xc02df400 CIScanner_SweepFile + 336
11 com.sophos.sav.savi 0xc01d7c3f CISavi2_SweepFile + 271
12 com.sophos.sum.scan.kit 0x0002276d -[SUMSAVIAdaptor scanFile:error:] + 67
13 com.sophos.sum.scan.kit 0x00022650 -[SUMSAVIAdaptor scanInfo:withExecutor:] + 74
14 com.sophos.sum.scan.kit 0x000280bf -[SUMScanningSweepWalker scanFile:] + 613
15 com.sophos.sum.scan.kit 0x0002062e sweepWalkerScanCallback + 101
16 com.sophos.sav.savi 0xc02fb9f7 sophosRecursiveWalk + 3975
17 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
18 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
19 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
20 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
21 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
22 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
23 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
24 com.sophos.sav.savi 0xc02faa0c sophosWalk + 460
25 com.sophos.sum.scan.kit 0x0001fdfb -[SUMSweepWalker walkScanItem:withExecutor:] + 297
26 com.sophos.sum.scan.kit 0x00027e27 -[SUMScanningSweepWalker walkScanItem:withExecutor:] + 176
27 com.sophos.sum.scan.kit 0x0002c580 -[SUMLocalVolumesScanExecutor lookForThreats] + 489
28 com.sophos.sum.scan.kit 0x0002a127 -[SUMScanExecutor(PrivateMethods) executeScan] + 607
29 com.sophos.sum.scan.kit 0x00029a8a -[SUMScanExecutor start] + 113
30 com.apple.Foundation 0x9340baed -[NSThread main] + 45
31 com.apple.Foundation 0x9340b896 __NSThread__main__ + 1538
32 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
33 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
34 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 8:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 9:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 10:
0 libsystem_kernel.dylib 0x995065be getdirentries + 10
1 libsystem_c.dylib 0x90228989 _readdir_unlocked + 104
2 libsystem_c.dylib 0x90228a28 readdir + 38
3 com.sophos.sav.savi 0xc0001d63 VENGi_readdir + 35
4 com.sophos.sav.savi 0xc01e921d sophosFindNext + 125
5 com.sophos.sav.savi 0xc02fc336 sophosRecursiveWalk + 6342
6 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
7 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
8 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
9 com.sophos.sav.savi 0xc02fc238 sophosRecursiveWalk + 6088
10 com.sophos.sav.savi 0xc02faa0c sophosWalk + 460
11 com.sophos.sum.scan.kit 0x0001fdfb -[SUMSweepWalker walkScanItem:withExecutor:] + 297
12 com.sophos.sum.scan.kit 0x00027906 -[SUMCountingSweepWalker walkScanItem:withExecutor:] + 1605
13 com.sophos.sum.scan.kit 0x0002a4ef -[SUMScanExecutor(PrivateMethods) findFileCount] + 277
14 com.sophos.sum.scan.kit 0x0002a022 -[SUMScanExecutor(PrivateMethods) executeScan] + 346
15 com.sophos.sum.scan.kit 0x00029a8a -[SUMScanExecutor start] + 113
16 com.apple.Foundation 0x9340baed -[NSThread main] + 45
17 com.apple.Foundation 0x9340b896 __NSThread__main__ + 1538
18 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
19 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
20 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 11:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 12:
0 libsystem_kernel.dylib 0x99505e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x920f42b1 _pthread_wqthread + 939
2 libsystem_pthread.dylib 0x920f1e2e start_wqthread + 30
Thread 13:
0 libsystem_kernel.dylib 0x99505e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x920f42b1 _pthread_wqthread + 939
2 libsystem_pthread.dylib 0x920f1e2e start_wqthread + 30
Thread 14:
0 libsystem_kernel.dylib 0x99505e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x920f42b1 _pthread_wqthread + 939
2 libsystem_pthread.dylib 0x920f1e2e start_wqthread + 30
Thread 15 Crashed:
0 com.apple.CoreFoundation 0x905905f7 ___TERMINATING_DUE_TO_UNCAUGHT_EXCEPTION___ + 7
1 com.apple.CoreFoundation 0x9058ff79 __raiseError + 985
2 libobjc.A.dylib 0x9b50aa2a objc_exception_throw + 276
3 com.apple.CoreFoundation 0x9058fb7d +[NSException raise:format:] + 141
4 com.apple.Foundation 0x933d3dfb -[NSFileManager fileSystemRepresentationWithPath:] + 125
5 com.apple.Foundation 0x933d3d68 -[NSString(NSPathUtilities) fileSystemRepresentation] + 63
6 SophosAVAgent 0x00005251 -[AdHocScanExecutor scanJob:] + 284
7 SophosAVAgent 0x00003e39 -[ScanChild(BackgroundScanning) backgroundScanWorker] + 680
8 com.apple.Foundation 0x9340baed -[NSThread main] + 45
9 com.apple.Foundation 0x9340b896 __NSThread__main__ + 1538
10 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
11 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
12 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 16:
0 libsystem_kernel.dylib 0x99506f42 __sem_wait + 10
1 com.sophos.sav.savi 0xc033bece SAVIplatWaitSemaphore + 222
2 com.sophos.sav.savi 0xc02c36fe SXLThread + 366
3 com.sophos.sav.savi 0xc033a6a7 startThread + 167
4 libsystem_pthread.dylib 0x920f3e13 _pthread_body + 138
5 libsystem_pthread.dylib 0x920f3d89 _pthread_start + 162
6 libsystem_pthread.dylib 0x920f1e52 thread_start + 34
Thread 15 crashed with X86 Thread State (32-bit):
eax: 0x00000001 ebx: 0x020e2420 ecx: 0x00000000 edx: 0x00000000
edi: 0x9058fbae esi: 0x01db3a00 ebp: 0xb072c418 esp: 0xb072c410
ss: 0x00000023 efl: 0x00000282 eip: 0x905905f7 cs: 0x0000001b
ds: 0x00000023 es: 0x00000023 fs: 0x00000023 gs: 0x0000000f
cr2: 0x016e0000
Logical CPU: 6
Error Code: 0x00000000
Trap Number: 3
This thread was automatically locked due to age.