This wasn't happening in the Stable build of Stencyl, so I am guessing this is OpenFL related.
when you pause Tiny Dangerous Dungeons, it opens a pause menu actor that displays you collected items as well as the world map. When pausing, it creates item and map icons depending on if you have found them or not. The small black squares on the map indicate hidden items, and if you have found the item, it doesn't spawn on the map anymore and the item's icon appears to the inventory. Unpausing the game kills the inventory/map screen and all the item and map icons.
However, when unpausing the game, this weird error message pops up. I did some testing and it only shows up when the small map squares are killed. It's weird, because those actors don't have anything else on them besides make self always simulate and anchor self to screen. They don't interact with anything at all.
Here's image of the inventory screen actor's event. I noticed that on the last part of it, if I only have 4 or less Create MapIcon blocks, like the nameless one, Glove, Knives and Boot, the pausing works normally, but the moment I add more, like Key1, the error pops up when unpausing the game.