codegen: add foreign key error check test

ops/gas_init_test.sh

@@ -9,7 +9,8 @@ set -e
 set -x
 
 PS4='+(${BASH_SOURCE}:${LINENO}): '
-cd "$(dirname "${BASH_SOURCE[0]}")/.."
+proj_root=$(readlink -f "$(dirname "${BASH_SOURCE[0]}")/..")
+cd "$proj_root"
 
 # Compile `gas`
 gas="/tmp/gas"
@@ -29,6 +30,9 @@ EOF
 
 cd $test_project
 
+# Add "replace" directive"
+echo "replace git.offline-twitter.com/offline-labs/gas-stack => $proj_root" >> go.mod
+
 # Create a new table in the schema
 cat >> pkg/db/schema.sql <<EOF
 create table item_flavor (rowid integer primary key, name text not null) strict;