Cryptic error message adding tarball "Breakpoint[on-fail]: caught error Error processing tar file(exit status 3): No help topic for '/'"

[CrazyCasta]

I'm trying to debug a Dockerfile that's failing with standard buildx. I get an error with buildg before the line that fails with buildx.

#7 68.21 Certificate added: C=CN, O="iTrusChina Co.,Ltd.", CN=vTrus Root CA
#7 68.21 140 new root certificates were added to your trust store.
#7 68.21 Import process completed.
#7 68.21 Done
#7 68.21 done.
#7 68.24 Processing triggers for libgdk-pixbuf-2.0-0:amd64 (2.42.10+dfsg-1+b1) ...
#7 DONE 68.4s

#8 [inst 1/6] RUN mkdir /build
#8 DONE 0.2s

#9 [inst 2/6] ADD Quartus-lite-17.0.2.602-linux.tar /build
Breakpoint[on-fail]: caught error Error processing tar file(exit status 3): No help topic for '/'

Filename: "Dockerfile"
     12| FROM pre-inst AS inst
     13| 
     14| RUN mkdir /build
 =>  15| ADD Quartus-lite-17.0.2.602-linux.tar /build
     16| ADD "https://ftp-osl.osuosl.org/pub/libpng/src/libpng12/libpng-1.2.59.tar.xz" \
     17|     /build
     18| 

I can add more context but I don't see anything more that seems relevant. As the title says, the error message is extremely cryptic as far as I'm concerned and I don't even know where to start with this. Again, the Dockerfile gets past this point with standard buildx.

The two commands that I run are: nerdctl builder debug . and docker build -f Dockerfile -t ${CONTAINER_AUTH} ..