ref https://en.cppreference.com/w/cpp/error/exception/what
> Pointer to a null-terminated string with explanatory information. The
pointer is guaranteed to be valid at least until the exception object
from which it is obtained is destroyed, or until a non-const member
function on the exception object is called.
The pointer is only valid before `CStdException as e` is destroyed
Old examples are broken on macOS arm64
```
/Users/blue/Desktop/nimony/test4.nim(38) test4
/Users/blue/Desktop/nimony/test4.nim(26) fn
/Users/blue/.choosenim/toolchains/nim-#devel/lib/std/assertions.nim(41) failedAssertImpl
/Users/blue/.choosenim/toolchains/nim-#devel/lib/std/assertions.nim(36) raiseAssert
/Users/blue/.choosenim/toolchains/nim-#devel/lib/system/fatal.nim(53) sysFatal
Error: unhandled exception: /Users/blue/Desktop/nimony/test4.nim(26, 3) `$b == "foo2"` [AssertionDefect]
```
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