[CRASH] Crash app while creating PDF

[khanhnt748]

0 flutter_html_to_pdf 0x0000000101f12994 Swift runtime failure: Unexpectedly found nil while implicitly unwrapping an Optional value + 0 (SwiftFlutterHtmlToPdfPlugin.swift:0)
1 flutter_html_to_pdf 0x0000000101f12994 closure #1 in closure #1 in SwiftFlutterHtmlToPdfPlugin.handle(:result:) + 820 (SwiftFlutterHtmlToPdfPlugin.swift:34)
2 flutter_html_to_pdf 0x0000000101f12698 closure #1 in closure #1 in SwiftFlutterHtmlToPdfPlugin.handle(:result:) + 56 (:0)
3 flutter_html_to_pdf 0x0000000101f12c60 thunk for @escaping @callee_guaranteed () -> () + 28 (:0)
4 libdispatch.dylib 0x0000000189bf0a30 _dispatch_client_callout + 20 (object.m:560)
5 libdispatch.dylib 0x0000000189bf3eec _dispatch_continuation_pop + 500 (inline_internal.h:2622)
6 libdispatch.dylib 0x0000000189c0713c _dispatch_source_invoke + 1596 (source.c:596)
7 libdispatch.dylib 0x0000000189bfee9c _dispatch_main_queue_drain + 756 (inline_internal.h:0)
8 libdispatch.dylib 0x0000000189bfeb98 _dispatch_main_queue_callback_4CF + 44 (queue.c:7770)
9 CoreFoundation 0x0000000189f41800 CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE + 16 (CFRunLoop.c:1795)
10 CoreFoundation 0x0000000189efb704 __CFRunLoopRun + 2532 (CFRunLoop.c:3144)
11 CoreFoundation 0x0000000189f0ebc8 CFRunLoopRunSpecific + 600 (CFRunLoop.c:3268)
12 GraphicsServices 0x00000001a607a374 GSEventRunModal + 164 (GSEvent.c:2200)
13 UIKitCore 0x000000018c882b58 -[UIApplication _run] + 1100 (UIApplication.m:3511)
14 UIKitCore 0x000000018c604090 UIApplicationMain + 364 (UIApplication.m:5064)
15 Runner 0x0000000100f025c0 main + 64 (AppDelegate.swift:10)
16 dyld 0x0000000101675da4 start + 520 (dyldMain.cpp:879)