Good catch, and thanks for pasting the whole stack trace — that one line named the exact file.

The NPC in the error is 9390306. Its animation data says the "falling" pose has six frames, but only frames 0 and 1 actually have pictures bundled with the game. In the original MapleStory files frames 2-5 aren't separate pictures at all, they're just pointers back at frames 0 and 1 — and the tool that packs our artwork skips pointers, so those four frames ended up with no image anywhere.

When a frame has no bundled image the game falls back to asking the server for the file directly. That folder was deleted when we moved all the artwork into bundles, so the server answers with the game's own web page instead of a picture, with a "success" code. Phaser accepts it, tries to decode it as a PNG, and throws exactly the error you saw.

I checked the whole NPC set: it's 28 NPCs and 430 frames, not just this one, so this is worth fixing properly rather than silencing. Two changes: (1) make the artwork generator follow those pointers so every frame points at a picture that really exists, then repack the NPC art bundles; (2) stop the game from asking the server for a file we know can't be there, so a gap can never turn into a decode error again.

It's noisy but harmless — the NPC still shows up, one or two frames of its falling animation just blink. Nothing is broken for you in-game.

Confirmed — thanks for catching the console error. It's noisy but harmless: the NPC (9390306, one of the falling Maple NPCs) still shows up, it just has a couple of frames of its falling animation missing. The original game files reuse frames by pointing at earlier ones instead of storing them twice, and our art-packing tool doesn't follow those pointers, so frames 2 to 5 aren't in the pack. The game was still asking the server for them, the server answered with the web page instead of an image, and Phaser threw that error while trying to decode it. It no longer asks for frames it knows aren't packed, so the error is gone. Getting those two frames actually drawing needs the art re-packed with pointer-following, which is a data job and isn't in this patch.