If currently a process exits after ptrace catched it but before sampling with perf_event_open has been set up, perf_event_open will throw ESRCH ("no such process"), aborting lo2s.
Instead, handle ESRCH more gracefully by printing a warning but otherwise ignoring the non-existent process.
If currently a process exits after ptrace catched it but before sampling with perf_event_open has been set up, perf_event_open will throw ESRCH ("no such process"), aborting lo2s.
Instead, handle ESRCH more gracefully by printing a warning but otherwise ignoring the non-existent process.
Fixes #320