fix: do not listen on SIGBUS, SIGFPE, SIGSEGV and SIGILL (#40)

Listening for one of these signals from JS will make the process
enter an infinite loop when encountering them naturally
because the underlying problem is not resolved while the signal
handler is being scheduled.

Ref: npm/npm#13782
Ref: nodejs/node#8410

Author: addaleax

signals.js

@@ -13,15 +13,16 @@
 // fatal signal like SIGWINCH or something, and then
 // exit, it'll end up firing `process.emit('exit')`, so
 // the handler will be fired anyway.
+//
+// SIGBUS, SIGFPE, SIGSEGV and SIGILL, when not raised
+// artificially, inherently leave the process in a
+// state from which it is not safe to try and enter JS
+// listeners.
 module.exports = [
   'SIGABRT',
   'SIGALRM',
-  'SIGBUS',
-  'SIGFPE',
   'SIGHUP',
-  'SIGILL',
   'SIGINT',
-  'SIGSEGV',
   'SIGTERM'
 ]