Flutter error on build: Command PhaseScriptExecution failed with a nonzero exit code

Question

I work on a flutter app (not mine) and I got trouble de repair the iOS folder.

When trying to build the project on Xcode i got an error :

 Command PhaseScriptExecution failed with a nonzero exit code

I tried to execute manually the build command and it's seems like an export failed :

$ > cd /Users/student/Documents/freelance/mysuperapp/mysuperapp/ios [...]
/// OUTPUT
export: not valid in this context: PROJECT:Runner-
$> echo $?
$> 1

Someone known how help me ?

The big build command (preview) :

PhaseScriptExecution Run\ Script /Users/student/Library/Developer/Xcode/DerivedData/Runner-fqocogpbgrmfqgfdjxpyoikjgecw/Build/Intermediates.noindex/ArchiveIntermediates/Runner/IntermediateBuildFilesPath/Runner.build/Release-iphoneos/Runner.build/Script-9740EEB61CF901F6004384FC.sh (in target 'Runner' from project 'Runner')
    cd /Users/student/Documents/freelance/mysuperapp/mysuperapp/ios
    export ACTION=install
    export AD_HOC_CODE_SIGNING_ALLOWED=NO
    export ALTERNATE_GROUP=staff
    export ALTERNATE_MODE=u+w,go-w,a+rX
    export ALTERNATE_OWNER=student
    export ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES=YES
 
   [...] REMOVED 26 000 CHARRACTER ELSE STACK OVERFLOW BLOCK POST

  
    export VERSIONPLIST_PATH=Runner.app/version.plist
    export VERSION_INFO_BUILDER=student
    export VERSION_INFO_FILE=Runner_vers.c
    export VERSION_INFO_STRING=""@(#)PROGRAM:Runner  PROJECT:Runner-""
    export WATCHKIT_2_SUPPORT_FOLDER_PATH=/Users/student/Library/Developer/Xcode/DerivedData/Runner-fqocogpbgrmfqgfdjxpyoikjgecw/Build/Intermediates.noindex/ArchiveIntermediates/Runner/BuildProductsPath/WatchKitSupport2
    export WATCHKIT_SUPPORT_FOLDER_PATH=/Users/student/Library/Developer/Xcode/DerivedData/Runner-fqocogpbgrmfqgfdjxpyoikjgecw/Build/Intermediates.noindex/ArchiveIntermediates/Runner/BuildProductsPath/WatchKitSupport
    export WRAPPER_EXTENSION=app
    export WRAPPER_NAME=Runner.app
    export WRAPPER_SUFFIX=.app
    export WRAP_ASSET_PACKS_IN_SEPARATE_DIRECTORIES=NO
    export XCODE_APP_SUPPORT_DIR=/Applications/Xcode.app/Contents/Developer/Library/Xcode
    export XCODE_PRODUCT_BUILD_VERSION=11E503a
    export XCODE_VERSION_ACTUAL=1141
    export XCODE_VERSION_MAJOR=1100
    export XCODE_VERSION_MINOR=1140
    export XPCSERVICES_FOLDER_PATH=Runner.app/XPCServices
    export YACC=yacc
    export arch=undefined_arch
    export variant=normal
    /bin/sh -c /Users/student/Library/Developer/Xcode/DerivedData/Runner-fqocogpbgrmfqgfdjxpyoikjgecw/Build/Intermediates.noindex/ArchiveIntermediates/Runner/IntermediateBuildFilesPath/Runner.build/Release-iphoneos/Runner.build/Script-9740EEB61CF901F6004384FC.sh

The big build command : http://pastiebin.com/embed/5fd34ee6a68bc