k+ segfaults on non-file command-line arguments

[paulapatience]

In a shell:

$ k+ @
0
^
Segmentation fault
$ echo >/tmp/a.k
$ k+ /tmp/a.k
ktye/k+
 ^C
$ k+ /tmp/a.k @
0
^
Segmentation fault

[talas]

The segfault might be caused by calling longjump without a prior setjmp. This can happen if a call to trap is made before the main repl loop.