same crash

as below picture:

iOS 14.0 (18A373)     0x196aceaf8 <+0>:  pacibsp      0x196aceafc <+4>:  sub    sp, sp, #0x20             ; =0x20      0x196aceb00 <+8>:  stp    x29, x30, [sp, #0x10]     0x196aceb04 <+12>: add    x29, sp, #0x10            ; =0x10      0x196aceb08 <+16>: stur   w1, [x29, #-0x4]>  0x196aceb0c <+20>: ldr    x8, [x0, #0x68]&#9;&#9;&#9;&#9;(WebThread (12): EXC_BAD_ACCESS (code=1, address=0xa0c20820001088))     0x196aceb10 <+24>: cmp    x8, w1, uxtw     0x196aceb14 <+28>: b.ls   0x196aceb30               ; <+56>     0x196aceb18 <+32>: and    x8, x1, #0xffffffff     0x196aceb1c <+36>: ldr    x9, [x0, #0x70]     0x196aceb20 <+40>: ldr    x8, [x9, x8, lsl #3]     0x196aceb24 <+44>: cmn    x8, #0x1                  ; =0x1      0x196aceb28 <+48>: csel   x0, xzr, x8, eq     0x196aceb2c <+52>: b      0x196aceb44               ; <+76> (lldb) reg read x8       x8 = 0x000000016fe2f4b0 (lldb) reg read x0       x0 = 0x00a0c20820001020 (lldb) im lookup -a 0x196aceb0c       Address: WebCore[0x000000018edb6b0c] (WebCore.TEXT.text + 35807676)       Summary: WebCore`gl::FramebufferManager::getFramebuffer(gl::FramebufferID) const + 20 can anybody help ? I can't find FramebufferManager class in the webcore sources.