Getting a crash after paint.

[Worik Stanton]

```

* thread #10, name = 'io.flutter.1.raster', stop reason = EXC_BAD_ACCESS (code=2, address=0x16bcd0000)

frame #0: 0x00000001f0b47aa8 libsystem_platform.dylib`_platform_memmove + 88

libsystem_platform.dylib`_platform_memmove:

-> 0x1f0b47aa8 <+88>: stnp q0, q1, [x3]

0x1f0b47aac <+92>: add x3, x3, #0x20

0x1f0b47ab0 <+96>: ldnp q0, q1, [x1]

0x1f0b47ab4 <+100>: add x1, x1, #0x20

Target 0: (Runner) stopped.

```

After the Painter.paint has run I am getting an occasional crash.  It is not in my code.  Is there any way to find out why?  This assembly dump is not much use.