I was poking around the wired tiger repo with the static analysis tool I worked on previously, one of the things that it found is this.

src/os_posix/os_fs.c

❯❯❱ cpp.lang.security.memory.null-deref.null-library-function.null-library-function
The `strrchr` function returns NULL on error and this line dereferences the return value without checking for NULL. Details: https://sg.run/OrLxp

130┆ strrchr(dir, '/')[1] = '\0';

 
That code is found here 

Discussing this with Keith, the thinking is this implicit assert is better replaced with an explicit WT_ASSERT_ALWAYS so that if it ever fires we get useful data back.