Fix improperly reported test exit code in github actions

Author: plemarquand

docker/test.sh

@@ -19,5 +19,10 @@ npm run lint
 npm run format
 npm run package
 
-(xvfb-run -a npm run coverage; echo $? > exitcode) | grep -Ev "Failed to connect to the bus|GPU stall due to ReadPixels" && rm -rf "${current_directory}/coverage" && (cp -R ./coverage "${current_directory}" || true)
-exit "$(<exitcode)"
+xvfb-run -a npm run coverage 2>&1 | grep -Ev "Failed to connect to the bus|GPU stall due to ReadPixels"
+exit_code=${PIPESTATUS[0]}
+
+rm -rf "${current_directory}/coverage"
+cp -R ./coverage $current_directory || true
+
+exit "${exit_code}"