iMovie crashes whenever I try to export?

Whichever file I try to export, iMovie crashes/fails to successfully export the file. What can I do to fix this?

Process:               iMovie [1164]
Path:                  /Users/USER/Desktop/iMovie.app/Contents/MacOS/iMovie
Identifier:            com.apple.iMovieApp
Version:               10.1 (271335)
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           iMovie [1164]
User ID:               501

Date/Time:             2019-01-02 20:15:12.138 -0600
OS Version:            Mac OS X 10.14 (18A391)
Report Version:        12

System Integrity Protection: enabled

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Application Specific Information:
*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil
abort() called

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	0x00007fff5e456b86 __pthread_kill + 10
1   libsystem_pthread.dylib       	0x00007fff5e50cc50 pthread_kill + 285
2   libsystem_c.dylib             	0x00007fff5e3c01c9 abort + 127
3   com.apple.Flexo               	0x000000010ee12d24 FFApplicationHandleExceptionThatShouldNotBeIgnored + 452
4   com.apple.AppKit              	0x00007fff2e7d282a -[NSApplication run] + 904
5   com.apple.prokit              	0x000000010dff642f NSProApplicationMain + 329
6   libdyld.dylib                 	0x00007fff5e318085 start + 1

Thread 19:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 20:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 21:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 22:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 23:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 24:
0   libsystem_pthread.dylib       	0x00007fff5e509408 start_wqthread + 0
1   ???                           	0x0000000054485244 0 + 1414025796

Thread 0 crashed with X86 Thread State (64-bit):
  rax: 0x0000000000000000  rbx: 0x000000011a3285c0  rcx: 0x00007ffee211f9a8  rdx: 0x0000000000000000
  rdi: 0x0000000000000307  rsi: 0x0000000000000006  rbp: 0x00007ffee211f9e0  rsp: 0x00007ffee211f9a8
   r8: 0x0000000000000000   r9: 0x0000000000000000  r10: 0x0000000000000000  r11: 0x0000000000000206
  r12: 0x0000000000000307  r13: 0x0000000000000001  r14: 0x0000000000000006  r15: 0x000000000000002d
  rip: 0x00007fff5e456b86  rfl: 0x0000000000000206  cr2: 0x00007fff903b4188
  
Logical CPU:     0
Error Code:      0x02000148
Trap Number:     133