getting crash with stack trace. what's the cause?

Mobi crashes when I attempt to load a downloaded pdf. here is the stack trace:
018-02-07 15:25:44.731558-0600 Endeavour[26431:2812613] File Path: /var/mobile/Containers/Data/Application/9EECA7E1-CC31-4A4B-8F3A-49FB8FA40090/Documents/cmsmobile_dl/201306031542.pdf
2018-02-07 15:25:44.974883-0600 Endeavour[26431:2812613] 0
2018-02-07 15:25:45.192498-0600 Endeavour[26431:2812613] THREAD WARNING: took '464.184326' ms. Plugin should use a background thread.
2018-02-07 15:25:45.226120-0600 Endeavour[26431:2812613] Invalid callback id received by sendPluginResult
2018-02-07 15:25:45.452818-0600 Endeavour[26431:2812613] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndexedSubscript:]: index 0 beyond bounds for empty array'
*** First throw call stack:
(0x183ee6364 0x18312c528 0x183e7ee9c 0x183e6bfb8 0x1006b38f0 0x1006a82a4 0x1006a8604 0x18d51dd2c 0x187f2956c 0x187e20a18 0x187f2f2fc 0x187f28f98 0x187e9a424 0x187ec1b90 0x18d48f5c8 0x183e8dedc 0x183e8b894 0x183e8be50 0x183dabe58 0x185c58f84 0x18d50067c 0x100664ddc 0x1838c856c)
libc++abi.dylib: terminating with uncaught exception of type NSException

We need more information:
Which version/platform are you using?
Can you send us the pdf causing the crash please?

nevermind. I found the problem. another thread had the file open at the same time RadaeePDF was trying to open it.

Can you please share some information about it (may be with a code snippet)?

We will investigate if we can avoid such a case.