valgrind displays errors

[martinellison]

• I ran the timer-cxx example from git@github.com:zserge/webview.git (at commit 16c93bc) under valgrind and received many errors.
• I ran examples from the rust crate and also received many similar errors; see Malloc issues with webview Boscop/web-view#79

What OS are you using (uname -a, or Windows version)?

Linux xiaosan 5.2.18-200.fc30.x86_64 #1 SMP Tue Oct 1 13:14:07 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

What programming language are you using (C/C++/Go/Rust)?

gcc (GCC) 9.2.1 20190827 (Red Hat 9.2.1-1)
rustc 1.38.0 (625451e37 2019-09-23)

What did you expect to see and what you saw instead?

Expected to see no errors when running under valgrind, found many errors.

Typical error

Thread 1:
==20991== Invalid write of size 8
==20991== at 0x90C845B: ??? (in /usr/lib64/libjavascriptcoregtk-4.0.so.18.13.7)
==20991== by 0x1FFEFFE05F: ???
==20991== by 0x1FFEFFE03F: ???
==20991== by 0x526FCBF: ???
==20991== by 0x23E829AF: ???
==20991== by 0x517254C: ??? (in /usr/lib64/libcairo.so.2.11600.0)
==20991== by 0x5174F67: ??? (in /usr/lib64/libcairo.so.2.11600.0)
==20991== by 0x1FFEFFE82F: ???
==20991== by 0x95EC021: WTF::fastFree(void*) (in /usr/lib64/libjavascriptcoregtk-4.0.so.18.13.7)
==20991== by 0x90C5AB8: ??? (in /usr/lib64/libjavascriptcoregtk-4.0.so.18.13.7)
==20991== by 0x486DD7F: ???
==20991== by 0x486F497: ???
==20991== Address 0x1ffeffd938 is on thread 1's stack
==20991== 512 bytes below stack pointer

[TomzBench]

i see lots of memory errors from just basic example on the README. Are these errors from the OS implementations or from the webview abstractions?