Hello @jeremiedb
DockerBuildError means that we were not able to install your dependencies.
The second error is a bit misleading. This is the complete traceback.
Error in doTryCatch(return(expr), name, parentenv, handler) :
[16:58:16] ./include/xgboost/json.h:65: Invalid cast, from Null to Array
Stack trace:
[bt] (0) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(dmlc::LogMessageFatal::~LogMessageFatal()+0x73) [0x7f88839d4df3]
[bt] (1) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(xgboost::JsonArray const* xgboost::Cast<xgboost::JsonArray const, xgboost::Value>(xgboost::Value*)+0x25c) [0x7f8883a6a05c]
[bt] (2) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(xgboost::RegTree::LoadModel(xgboost::Json const&)+0x3ab) [0x7f88839f94bb]
[bt] (3) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(xgboost::gbm::GBTreeModel::LoadModel(xgboost::Json const&)+0x3d9) [0x7f88839f8c89]
[bt] (4) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(xgboost::gbm::GBTree::LoadModel(xgboost::Json const&)+0x183) [0x7f88839f8fe3]
[bt] (5) /usr/local/lib/R/site-library/xgboost/libs/xgboost.so(xgboost::LearnerIO::LoadModel(xgboost::Json const&)+0x4d1) [0x7f8883abea81]
[bt] (6) /usr