Make psh/pul error out if no registers given While the generated object code was technically correct for bare pshs, puls, pshu, and pulu, it was not helpful. Throw a bad operand error if no registers are given as an operand to such instructions. Thanks to Erik G <erik@6809.org> for reporting the problem.

--- a/lwasm/insn_rlist.c	Mon Jun 15 21:21:58 2015 -0600
+++ b/lwasm/insn_rlist.c	Mon Jun 15 21:26:33 2015 -0600
@@ -55,6 +55,8 @@
 			rn = 1 << rn;
 		rb |= rn;
 	}
+	if (rb == 0)
+		lwasm_register_error(as, l, "Bad operand");
 	l -> len = OPLEN(instab[l -> insn].ops[0]) + 1;
 	l -> pb = rb;
 }