Possible panic in dockerfile frontend

[jedevc]

https://github.com/moby/buildkit/runs/7856267216?check_suite_focus=true

+ docker buildx build --file ./hack/dockerfiles/lint.Dockerfile . --progress=plain
#1 [internal] load build definition from lint.Dockerfile
#1 transferring dockerfile: 632B done
#1 DONE 0.0s

#2 [internal] load .dockerignore
#2 transferring context: 56B done
#2 DONE 0.0s

#3 resolve image config for docker.io/docker/dockerfile-upstream:master
#3 ...

#4 [auth] docker/dockerfile-upstream:pull token for registry-1.docker.io
#4 DONE 0.0s

#3 resolve image config for docker.io/docker/dockerfile-upstream:master
#3 DONE 2.6s

#5 docker-image://docker.io/docker/dockerfile-upstream:master@sha256:0775f71875f6a4945e0f7ee8eeb47fedb0caff79eb971ec799522eecc81491f6
#5 resolve docker.io/docker/dockerfile-upstream:master@sha256:0775f71875f6a4945e0f7ee8eeb47fedb0caff79eb971ec799522eecc81491f6 done
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 2.10MB / 10.52MB 0.2s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 3.15MB / 10.52MB 0.5s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 4.19MB / 10.52MB 0.6s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 5.24MB / 10.52MB 0.8s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 6.29MB / 10.52MB 1.1s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 7.34MB / 10.52MB 1.2s
#5 sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 10.52MB / 10.52MB 1.3s done
#5 extracting sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f
#5 extracting sha256:e3a5f9fd70fbf48b85c4c780a02a16a6a208da460dc04740c40141cf13147a5f 3.5s done
#5 DONE 4.8s
lint.Dockerfile:1
--------------------
   1 | >>> # syntax=docker/dockerfile-upstream:master
   2 |     
   3 |     FROM golang:1.18-alpine
--------------------
error: failed to solve: frontend grpc server closed unexpectedly
Error: Process completed with exit code 1.

It looks like something in a recent dockerfile update caused this to panic? Hopefully #3035 should help to provide some more visibility of this if it happens again in the future.