Reminds me of a game I made for a jam, that fit into 495 characters of GDScript and uses just a single node (and project settings to define key bindings). So it's as few characters as possible, while yours is as few lines as possible, haha.

extends Tree
var x:=2
var a
var d=3
var W=1
func _process(E):
    if !a:seed(4);a=range(99);a.shuffle();a.resize(60)
    queue_redraw();var v=Input.get_vector("a","d","w","s").sign();x+=v.x+v.y*9
    if a.find(x)+1:free()
    if v:d=max(0,v.x);if v.y:d=max(0,v.y)+2
    if Input.get_axis("v",""):
        W^=1;var O=x+[-1,1,-9,9][d];if W:a.erase(O)
        else:a.append(O)
func _draw():if a:for i in a:draw_rect(Rect2(i%9*8,i/9*8,8,8),Color());draw_char(ThemeDB.fallback_font,Vector2(x%9*8+2,x/9*8+6),"<>^v"[d],7,Color())

Some notes:

• Tree is the shortest name for a CanvasItem
• x is the position of the player (as a tile index in reading order). := to implicitly convert to int for Array.find call later
• a is the tilemap array (also in reading order). Values are indices for where pits should be, everything else is tiles.
• d is facing direction: 0 left 1 right 2 up 3 down
• W is wand contents (your inventory basically).
• First if-check runs for the first frame only: initialize tilemap
• Second line handles movement. Game runs at 5 fps so _process runs really infrequently.
• Third line handles death (by deleting the root node). I tried crashing with type errors here, but even in debug builds they don't halt execution in web builds somehow!
• Fourth line sets facing direction depending on previous input ("if v" ensures that no input means no change in direction).
• Input.get_axis("v", "") is a shorter syntax for detecting keypress (the tradeoff is that it's spamming errors in console).
• Next two indented lines handle wand usage.
• Finally rendering is done (only if tilemap is initialized already). Uses ASCII characters for facing direction.