[16:55:44] [Server thread/INFO]: Saving and pausing game...
[16:55:44] [Server thread/INFO]: Saving chunks for level 'ServerLevel[New World]'/minecraft:overworld
[16:55:44] [Server thread/INFO]: Saving chunks for level 'ServerLevel[New World]'/minecraft:the_nether
[16:55:44] [Server thread/INFO]: Saving chunks for level 'ServerLevel[New World]'/minecraft:the_end
[16:55:52] [Render thread/ERROR]: Error executing task on Client
java.lang.NullPointerException: Cannot invoke "net.minecraft.class_1263.method_5447(int, net.minecraft.class_1799)" because "this.field_7871" is null
 at net.minecraft.class_1735.method_44206(class_1735.java:66) ~[client-intermediary.jar:?]
 at net.minecraft.class_1703.method_7610(class_1703.java:592) ~[client-intermediary.jar:?]
 at net.minecraft.class_634.method_11153(class_634.java:1110) ~[client-intermediary.jar:?]
 at net.minecraft.class_2649.method_11439(class_2649.java:44) ~[client-intermediary.jar:?]
 at net.minecraft.class_2649.method_11054(class_2649.java:11) ~[client-intermediary.jar:?]
 at net.minecraft.class_2600.method_11072(class_2600.java:22) ~[client-intermediary.jar:?]
 at net.minecraft.class_1255.method_18859(class_1255.java:157) [client-intermediary.jar:?]
 at net.minecraft.class_4093.method_18859(class_4093.java:23) [client-intermediary.jar:?]
 at net.minecraft.class_1255.method_16075(class_1255.java:131) [client-intermediary.jar:?]
 at net.minecraft.class_1255.method_5383(class_1255.java:116) [client-intermediary.jar:?]
 at net.minecraft.class_310.method_1523(class_310.java:1129) [client-intermediary.jar:?]
 at net.minecraft.class_310.method_1514(class_310.java:768) [client-intermediary.jar:?]
 at net.minecraft.client.main.Main.method_44604(Main.java:244) [client-intermediary.jar:?]
 at net.minecraft.client.main.Main.main(Main.java:51) [client-intermediary.jar:?]
 at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:461) [fabric-loader-0.14.10.jar:?]
 at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74) [fabric-loader-0.14.10.jar:?]
 at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23) [fabric-loader-0.14.10.jar:?]
 at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
 at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[?:?]
 at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
 at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?]
 at org.prismlauncher.impl.OneSixLauncher.invokeMain(OneSixLauncher.java:104) [NewLaunch.jar:?]
 at org.prismlauncher.impl.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:176) [NewLaunch.jar:?]
 at org.prismlauncher.impl.OneSixLauncher.launch(OneSixLauncher.java:186) [NewLaunch.jar:?]
 at org.prismlauncher.EntryPoint.listen(EntryPoint.java:144) [NewLaunch.jar:?]
 at org.prismlauncher.EntryPoint.main(EntryPoint.java:74) [NewLaunch.jar:?]
[16:55:54] [Server thread/INFO]: Saving and pausing game...

this error comes up every time i try

You shouldn't even be able to, as they're only "inventory slots" just to be recognized by the screen. Annoying that it crashes.

It doesnt crash, it just throws an error. Is it possible to enable this functionality? I assume doing so will also allow items that are picked up to stack into the pouches instead of going just to your inventory

The error itself was unrelated to shift clicking and did it on every slot click, which has now been fixed.

Figuring out how to intercept shift clicking will be added later down the line