The following partial code $($CODE $3)$ for a FSM contains $1$ or more errors,

how many errors are there $?$

$($one numeric answer in range $0$ to $8)$

CODE $3$

localparam ST$0=1$;

localparam ST$1=2$;

localparam ST$2=3$;

localparam ST$3=0$;

always @$($posedge clk or negedge nrst$)$

if $(!$nrst$)$ state $<=$ ST$0$; else state $=$ nextstate;

always @$(*)$

case $($state$)$

ST$0$: if $($a$)$ nextstate $=$ ST$1$;

ST$1$: if $($b$)$ nextstate $=$ ST$0$; else nextstate $=$ ST$1$;

ST$2$: if $($a$)$ nextstate $=$ ST$3$;

ST$3$: if $($b$)$ nextstate $=$ ST$0$; else nextstate $=$ ST$3$;

default:

endcase

always @$(*)$

if $($state $==$ ST$3)$ d $=1$;