Docker build failed
Hello,

I try to build a Docker image of a the last source of nitter, but it failed : 

```
$ docker build -t nitter:latest .
Sending build context to Docker daemon  5.829MB
Step 1/13 : FROM nimlang/nim:alpine as nim
 ---> 2b2a582b9729
Step 2/13 : MAINTAINER setenforce@protonmail.com
 ---> Running in df843be52ea7
Removing intermediate container df843be52ea7
 ---> 2cf7f7ee469f
Step 3/13 : EXPOSE 8080
 ---> Running in 8afc975539e4
Removing intermediate container 8afc975539e4
 ---> 18392a0c8ff4
Step 4/13 : RUN apk --no-cache add libsass-dev libffi-dev openssl-dev redis openssh-client
 ---> Running in 59b98581b09c
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
(1/12) Upgrading libcrypto1.1 (1.1.1g-r0 -> 1.1.1i-r0)
(2/12) Upgrading libssl1.1 (1.1.1g-r0 -> 1.1.1i-r0)
(3/12) Installing linux-headers (5.4.5-r1)
(4/12) Installing pkgconf (1.7.2-r0)
(5/12) Installing libffi-dev (3.3-r2)
(6/12) Installing libsass (3.6.4-r0)
(7/12) Installing libsass-dev (3.6.4-r0)
(8/12) Installing openssh-keygen (8.3_p1-r1)
(9/12) Installing libedit (20191231.3.1-r0)
(10/12) Installing openssh-client (8.3_p1-r1)
(11/12) Installing openssl-dev (1.1.1i-r0)
(12/12) Installing redis (5.0.9-r0)
Executing redis-5.0.9-r0.pre-install
Executing redis-5.0.9-r0.post-install
Executing busybox-1.31.1-r16.trigger
Executing ca-certificates-20191127-r4.trigger
OK: 331 MiB in 62 packages
Removing intermediate container 59b98581b09c
 ---> 61c65f5348af
Step 5/13 : COPY . /src/nitter
 ---> b3ba7177f094
Step 6/13 : WORKDIR /src/nitter
 ---> Running in 06dc43986f0d
Removing intermediate container 06dc43986f0d
 ---> dcf73dac3dfc
Step 7/13 : RUN nimble build -y -d:release --passC:"-flto" --passL:"-flto"     && strip -s nitter     && nimble scss
 ---> Running in 223141e71c33
  Verifying dependencies for nitter@0.1.0
    Prompt: No local packages.json found, download it from internet? -> [forced yes]
Downloading Official package list
    Success Package list downloaded.
 Installing jester@>= 0.5.0
Downloading https://github.com/dom96/jester using git
  Verifying dependencies for jester@0.5.0
 Installing httpbeast@>= 0.2.2
Downloading https://github.com/dom96/httpbeast using git
  Verifying dependencies for httpbeast@0.2.2
 Installing https://github.com/timotheecour/asynctools@#pr_fix_compilation
Downloading https://github.com/timotheecour/asynctools using git
  Verifying dependencies for asynctools@#pr_fix_compilation
 Installing asynctools@#pr_fix_compilation
   Success: asynctools installed successfully.
 Installing httpbeast@0.2.2
   Success: httpbeast installed successfully.
      Info: Dependency on https://github.com/timotheecour/asynctools@#pr_fix_compilation already satisfied
  Verifying dependencies for asynctools@#pr_fix_compilation
 Installing jester@0.5.0
   Success: jester installed successfully.
 Installing karax@>= 1.1.2
Downloading https://github.com/pragmagic/karax using git
  Verifying dependencies for karax@1.2.1
 Installing ws@any version
Downloading https://github.com/treeform/ws using git
  Verifying dependencies for ws@0.4.3
 Installing ws@0.4.3
   Success: ws installed successfully.
 Installing dotenv@any version
Downloading https://github.com/euantorano/dotenv.nim using git
  Verifying dependencies for dotenv@1.1.1
 Installing dotenv@1.1.1
   Success: dotenv installed successfully.
 Installing karax@1.2.1
   Building karax/karax/tools/karun using c backend
   Success: karax installed successfully.
 Installing sass@#e683aa1
Downloading https://github.com/dom96/sass using git
  Verifying dependencies for sass@#e683aa1
 Installing sass@#e683aa1
   Success: sass installed successfully.
 Installing regex@#2e32fdc
Downloading https://github.com/nitely/nim-regex using git
  Verifying dependencies for regex@#2e32fdc
 Installing unicodedb@>= 0.7.2
Downloading https://github.com/nitely/nim-unicodedb using git
  Verifying dependencies for unicodedb@0.9.0
 Installing unicodedb@0.9.0
   Success: unicodedb installed successfully.
 Installing unicodeplus@>= 0.5.0
Downloading https://github.com/nitely/nim-unicodeplus using git
  Verifying dependencies for unicodeplus@0.8.0
      Info: Dependency on unicodedb@>= 0.8 already satisfied
  Verifying dependencies for unicodedb@0.9.0
 Installing segmentation@>= 0.1
Downloading https://github.com/nitely/nim-segmentation using git
  Verifying dependencies for segmentation@0.1.0
      Info: Dependency on unicodedb@>= 0.8.0 already satisfied
  Verifying dependencies for unicodedb@0.9.0
 Installing segmentation@0.1.0
   Success: segmentation installed successfully.
 Installing unicodeplus@0.8.0
   Success: unicodeplus installed successfully.
 Installing regex@#2e32fdc
   Success: regex installed successfully.
 Installing nimcrypto@>= 0.4.11
Downloading https://github.com/cheatfate/nimcrypto using git
  Verifying dependencies for nimcrypto@0.5.4
 Installing nimcrypto@0.5.4
   Success: nimcrypto installed successfully.
 Installing markdown@#abdbe5e
Downloading https://github.com/soasme/nim-markdown using git
  Verifying dependencies for markdown@#abdbe5e
 Installing markdown@#abdbe5e
   Building markdown/markdown using c backend
   Success: markdown installed successfully.
 Installing packedjson@#7198cc8
Downloading https://github.com/Araq/packedjson using git
  Verifying dependencies for packedjson@#7198cc8
 Installing packedjson@#7198cc8
   Success: packedjson installed successfully.
 Installing supersnappy@#1.1.5
Downloading https://github.com/guzba/supersnappy using git
  Verifying dependencies for supersnappy@#1.1.5
 Installing supersnappy@#1.1.5
   Success: supersnappy installed successfully.
 Installing redpool@#57aeb25
Downloading https://github.com/zedeus/redpool using git
  Verifying dependencies for redpool@#57aeb25
 Installing https://github.com/zedeus/redis@#94bcbf1
Downloading https://github.com/zedeus/redis using git
  Verifying dependencies for redis@#94bcbf1
 Installing redis@#94bcbf1
   Success: redis installed successfully.
 Installing redpool@#57aeb25
   Success: redpool installed successfully.
      Info: Dependency on https://github.com/zedeus/redis@#94bcbf1 already satisfied
  Verifying dependencies for redis@#94bcbf1
 Installing https://github.com/disruptek/frosty@#0.3.1
Downloading https://github.com/disruptek/frosty using git
  Verifying dependencies for frosty@#0.3.1
 Installing https://github.com/narimiran/sorta@< 1.0.0
Downloading https://github.com/narimiran/sorta using git
  Verifying dependencies for sorta@0.2.0
 Installing sorta@0.2.0
   Success: sorta installed successfully.
 Installing https://github.com/disruptek/criterion@< 1.0.0
Downloading https://github.com/disruptek/criterion using git
  Verifying dependencies for criterion@0.2.7
 Installing https://github.com/disruptek/balls@>= 2.0.0 & < 3.0.0
Downloading https://github.com/disruptek/balls using git
  Verifying dependencies for balls@2.4.3
 Installing https://github.com/disruptek/grok@>= 0.5.0 & < 1.0.0
Downloading https://github.com/disruptek/grok using git
  Verifying dependencies for grok@0.5.0
 Installing grok@0.5.0
   Success: grok installed successfully.
 Installing https://github.com/disruptek/ups@< 1.0.0
Downloading https://github.com/disruptek/ups using git
  Verifying dependencies for ups@0.0.5
 Installing npeg@>= 0.23.2 & < 1.0.0
Downloading https://github.com/zevv/npeg using git
  Verifying dependencies for npeg@0.24.1
 Installing npeg@0.24.1
   Success: npeg installed successfully.
 Installing ups@0.0.5
   Success: ups installed successfully.
 Installing balls@2.4.3
   Building balls/balls using c backend
oserr.nim(94)            raiseOSError
Error: unhandled exception: File exists
Additional info: "/tmp/nimble_7/githubcom_disruptekballs_2.0.0_3.0.0/balls" [OSError]
The command '/bin/sh -c nimble build -y -d:release --passC:"-flto" --passL:"-flto"     && strip -s nitter     && nimble scss' returned a non-zero code: 1
```

Build is launch on Debian 10, with docker-ce 5:20.10.2~3-0~debian-buster.

I don't fin any issue related to this error, can you please help me ?

Thanks,
Julien