Same here.
Running the forge installer it chokes on the minecraft jar file halfway:
$ tail -n 20 forge-1.14.4-28.1.0-installer.jar.log
Data assets/minecraft/textures/gui/stream_indicator.png
Data assets/minecraft/textures/gui/presets/drought.png
Data assets/minecraft/textures/gui/presets/isles.png
Data assets/minecraft/textures/gui/presets/luck.png
Data assets/minecraft/textures/gui/presets/delight.png
Data assets/minecraft/textures/gui/presets/chaos.png
Data assets/minecraft/textures/gui/presets/water.png
Data assets/minecraft/textures/gui/presets/madness.png
Data assets/minecraft/textures/gui/book.png
Data assets/minecraft/textures/gui/accessibility.png
Data assets/minecraft/textures/gui/title/mojang.png
Data assets/minecraft/textures/gui/title/background/panorama_1.png
Data assets/minecraft/textures/gui/title/background/panorama_2.png
Data assets/minecraft/textures/gui/title/background/panorama_4.png
Data assets/minecraft/textures/gui/title/background/panorama_0.png
Data assets/minecraft/textures/gui/title/background/panorama_overlay.png
Data assets/minecraft/textures/gui/title/background/panorama_3.png
Data assets/minecraft/textures/gui/title/background/panorama_5.png
Failed to run processor: java.io.EOFException:Unexpected end of ZLIB input stream
See log for more details.
$
OSX 10.14.6
Oracle JDK 13.0.1
Minecraft 1.15
FWIW, I'm getting the same error trying to manually un-jar Minecraft's ~/Library/Application Support/minecraft/versions/1.14.4/1.14.4.jar
$ jar -xfv 1.14.4.jar
...
inflated: assets/minecraft/textures/gui/presets/madness.png
inflated: assets/minecraft/textures/gui/book.png
inflated: assets/minecraft/textures/gui/accessibility.png
inflated: assets/minecraft/textures/gui/title/mojang.png
inflated: assets/minecraft/textures/gui/title/background/panorama_1.png
inflated: assets/minecraft/textures/gui/title/background/panorama_2.png
inflated: assets/minecraft/textures/gui/title/background/panorama_4.png
inflated: assets/minecraft/textures/gui/title/background/panorama_0.png
inflated: assets/minecraft/textures/gui/title/background/panorama_overlay.png
inflated: assets/minecraft/textures/gui/title/background/panorama_3.png
java.io.EOFException: Unexpected end of ZLIB input stream
at java.base/java.util.zip.InflaterInputStream.fill(InflaterInputStream.java:245)
at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:159)
at java.base/java.util.zip.ZipInputStream.read(ZipInputStream.java:195)
at java.base/java.util.zip.ZipInputStream.closeEntry(ZipInputStream.java:141)
at jdk.jartool/sun.tools.jar.Main.extractFile(Main.java:1456)
at jdk.jartool/sun.tools.jar.Main.extract(Main.java:1363)
at jdk.jartool/sun.tools.jar.Main.run(Main.java:409)
at jdk.jartool/sun.tools.jar.Main.main(Main.java:1680)
$ jar --version
jar 13.0.1
$ java --version
java 13.0.1 2019-10-15
Java(TM) SE Runtime Environment (build 13.0.1+9)
Java HotSpot(TM) 64-Bit Server VM (build 13.0.1+9, mixed mode, sharing)
$
Erik