#N canvas 511 225 762 387 10;
#X obj 127 161 dac~;
#X obj 128 101 line~;
#X obj 128 40 loadbang;
#X msg 128 71 220;
#X msg 199 70 \$1 1000;
#X obj 199 40 r freq;
#X obj 128 130 phasor~;
#X obj 231 117 print;
#X connect 1 0 6 0;
#X connect 2 0 3 0;
#X connect 3 0 1 0;
#X connect 4 0 1 0;
#X connect 4 0 7 0;
#X connect 5 0 4 0;
#X connect 6 0 0 0;
#X connect 6 0 0 1;
Click on $1 1000 with Edit Mode off in this example, and you'll get the error invalid [line~] value $1, instead of just passing zero value.