armbian-next: introduce assert_prepared_host() and assert before using any Python, to un-mask any further fallacies

lib/functions/configuration/aggregation.sh

@@ -2,7 +2,7 @@
 
 function assert_requires_aggregation() {
 	if [[ ${aggregation_has_already_run:-0} -lt 1 ]]; then
-		exit_with_error "assert_requires_aggregation: Aggregation has not been run"
+		exit_with_error "assert_requires_aggregation: Aggregation has not been run. This is a bug in armbian-next code. Please report!"
 	fi
 }
 

lib/functions/general/python-tools.sh

@@ -15,6 +15,7 @@ function early_prepare_pip3_dependencies_for_python_tools() {
 
 # call: prepare_python_and_pip # this defines global PYTHON3_INFO dict and PYTHON3_VARS array
 function prepare_python_and_pip() {
+	assert_prepared_host # this needs a prepared host to work; avoid fake errors about "python3-pip" not being installed
 	# First determine with python3 to use; requires knowing the HOSTRELEASE.
 	[[ -z "${HOSTRELEASE}" ]] && exit_with_error "HOSTRELEASE is not set"
 

lib/functions/host/prepare-host.sh

@@ -10,6 +10,12 @@ function prepare_host() {
 	return 0
 }
 
+function assert_prepared_host() {
+	if [[ ${prepare_host_has_already_run:-0} -lt 1 ]]; then
+		exit_with_error "assert_prepared_host: Host has not yet been prepared. This is a bug in armbian-next code. Please report!"
+	fi
+}
+
 function check_basic_host() {
 	display_alert "Checking" "basic host setup" "info"
 	obtain_and_check_host_release_and_arch # sets HOSTRELEASE and validates it for sanity; also HOSTARCH
@@ -185,6 +191,8 @@ function prepare_host_noninteractive() {
 	# Reset owner of userpatches if so required
 	reset_uid_owner "${USERPATCHES_PATH}" # Fix owner of files in the final destination
 
+	declare -i -g -r prepare_host_has_already_run=1 # global, readonly.
+
 	return 0
 }