ignore lines without commands

src/main.zig

@@ -208,6 +208,10 @@ pub fn doRepl(allocator: *std.mem.Allocator, args_it: var) !void {
             std.debug.warn("repl: error while parsing: {}\n", .{err});
             continue;
         };
+
+        // no command? ignore!
+        if (cmds_parsed.items.len == 0) continue;
+
         current = cmds_parsed.items[0].*;
 
         // by cloning the parent runner, we can iteratively write