Error AtlasBuilder.cpp:1266: Not a PNG file: PoweredFloorExtended/graphic/Flooring/Default/tile.png; mods: alien-biomes PoweredFloorExtended

it turns out that tile.png is currently a jpg-File

but..........it's a png.........

Is this on start-up or does it happen when you are doing something?
As I've just gone sandbox new game with those two mods and it works fine for me

found another 10 tile.png files which are not of PNG but JPG format:

./Flooring/Hex-Red/icon/tile.png
./Flooring/Hex-Red/tile.png
./Flooring/Hex-White/icon/tile.png
./Flooring/Hex-White/tile.png
./Flooring/Solar-Blue/icon/tile.png
./Flooring/Solar-Blue/tile.png
./Flooring/Tile-Blue/icon/tile.png
./Flooring/Tile-Blue/tile.png
./Flooring/Tile-Red/icon/tile.png
./Flooring/Tile-Red/tile.png

and it would be nice when you package the correct directory name into the zip file.
Currently the directory name does not correspond to the nod name in info.json

Powered-Flooring-Extended instead of PoweredFloorExtended

hmmmmmm, the JPG format I have no idea, the directory name is a mistake in me zipping the source control instead of the actual directory. I'll get that sorted. The only thing I can think of for the images would be to open them in an image editor and specifically export/save them as png so it's not ambiguous.

the error message triggers while loading the game, and i can confirm that those tile.png files contain jpg data

e.g.: ./Flooring/Alt-Grey/icon/grid.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 64x64, frames 3

for fixing it for me i then renamed the original files to tile.jpg and converted them using the following command:
jpegtopnm <tile.jpg | pnmtopng >tile.png

after these tweaks the game loads into the main menu

sorry to say but Version 0.0.14 does not fix the jpg-Problem, at least the directory structure works after unpacking.
You still have the .git Directory included.
Here is the list of files with the output of the file command:
PoweredFloorExtended_0.0.14/graphic/Flooring/Alt-Grey/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, progressive, precision 8, 1024x1024, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Hex-Red/icon/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 32x32, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Hex-Red/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, progressive, precision 8, 1024x1024, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Hex-White/icon/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 96x96, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], comment: "Created by fCoder Graphic Processor", baseline, precision 8, 32x32, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Hex-White/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 96x96, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], comment: "Created by fCoder Graphic Processor", baseline, precision 8, 1024x1024, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Solar-Blue/icon/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 28x28, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 32x32, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Solar-Blue/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 28x28, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 1024x1024, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Tile-Blue/icon/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 32x32, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Tile-Blue/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, progressive, precision 8, 1024x1024, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Tile-Red/icon/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=1, orientation=upper-left], baseline, precision 8, 32x32, frames 3

PoweredFloorExtended_0.0.14/graphic/Flooring/Tile-Red/tile.png: JPEG image data, JFIF standard 1.01, resolution (DPI), density 72x72, segment length 16, progressive, precision 8, 1024x1024, frames 3

Yeah, it was late so I only had time to sort out the directory. I don't have a lot of time today so it will likely be tomorrow that I can sort out the image thing.