installer + Dockerfile: keep set -u out of user's .bashrc

The previous fix wrapped the installer's 'source /opt/ros/noetic/setup.bash'
call with 'set +u; ...; set -u' via a Dockerfile sed. But the same sed
also caught the literal 'source /opt/ros/noetic/setup.bash' string
inside the installer's `echo "source ..." >> ~/.bashrc` line. The
wrapped string then got echoed into the user's .bashrc, leaving every
interactive shell with `set -u` active. Any ROS bash helper that
references positional args without defaults (roscd $1, rosls $1, ...)
errored out with 'bash: $1: unbound variable'.

Fix in the installer itself: wrap the actual source calls inline with
explicit `set +u` / `set -u` lines (two places — install_ros_noetic
and build_workspace). The literal `echo ... >> .bashrc` lines stay
plain, so the bashrc gets a clean source command that doesn't toggle
nounset.

Dockerfile: drop the two sed lines that wrapped the bashrc echoes;
they're no longer needed.

Verified: .bashrc now ends with
  source /opt/ros/noetic/setup.bash
  source /home/uniros/uniros_ws/devel/setup.bash
Interactive shells have nounset off, roscd / rosls / etc. work.

Author: ncbdrck

docker/Dockerfile

@@ -112,8 +112,6 @@ WORKDIR /home/${USERNAME}
 # user's HOME so bind mounts on a host with matching UID work cleanly.
 COPY --chown=${USERNAME}:${USERNAME} install_uniros_stack.sh /tmp/install_uniros_stack.sh
 RUN chmod +x /tmp/install_uniros_stack.sh \
-    && sed -i 's@source /opt/ros/noetic/setup.bash@set +u; source /opt/ros/noetic/setup.bash; set -u@' /tmp/install_uniros_stack.sh \
-    && sed -i 's@source "$WORKSPACE_PATH/devel/setup.bash" || true@set +u; source "$WORKSPACE_PATH/devel/setup.bash" || true; set -u@' /tmp/install_uniros_stack.sh \
     && UNIROS_INSTALL_IN_DOCKER=1 \
        /tmp/install_uniros_stack.sh -y -p /home/${USERNAME}/uniros_ws \
     && sudo rm -f /tmp/install_uniros_stack.sh \

install_uniros_stack.sh

@@ -194,8 +194,13 @@ install_ros_noetic() {
     if ! grep -q "source /opt/ros/noetic/setup.bash" "$HOME/.bashrc"; then
         echo "source /opt/ros/noetic/setup.bash" >> "$HOME/.bashrc"
     fi
+    # ROS setup.bash references variables that may be unset (and ROS
+    # bash helpers like roscd reference $1 in function bodies); both
+    # blow up under `set -u`. Disable nounset just for the source call.
     # shellcheck disable=SC1091
+    set +u
     source /opt/ros/noetic/setup.bash
+    set -u
     apt_install python3-rosdep python3-rosinstall python3-rosinstall-generator \
                 python3-wstool python3-catkin-tools build-essential \
         || fail "Failed to install ROS build tools"
@@ -416,8 +421,13 @@ build_workspace() {
 EOF
         ok "Created ~/.bash_profile (delegates to ~/.bashrc)."
     fi
+    # Same `set -u` deal as install_ros_noetic — disable nounset for
+    # the source so workspace setup.bash and ROS bash helpers don't
+    # explode on unset references.
     # shellcheck disable=SC1090
+    set +u
     source "$WORKSPACE_PATH/devel/setup.bash" || true
+    set -u
     ok "Workspace built."
 }