Fix SOURCE command safety issues (HIGH priority)

Added existence checks and error handling for all source commands
to prevent silent failures when dependencies are missing.

Library files (use 'return' for error):
- reference-db.sh: Added checks for 3 dependencies
- mysql-analyzer.sh: Added checks for 3 dependencies
- domain-discovery.sh: Added checks for 2 dependencies
- system-detect.sh: Added check for common-functions.sh
- plesk-helpers.sh: Added check for common-functions.sh
- user-manager.sh: Added checks for 2 dependencies

Executable scripts (use 'exit' for error):
- wordpress-cron-manager.sh: Added checks for 2 dependencies
- website-error-analyzer.sh: Added checks for 4 dependencies

Pattern: [ -f "file" ] && source "file" || { echo "ERROR" >&2; return/exit 1; }

This ensures scripts fail fast with clear error messages when
required dependencies are missing, rather than continuing with
undefined functions.

lib/domain-discovery.sh

@@ -8,8 +8,9 @@
 # Source dependencies
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$SCRIPT_DIR/common-functions.sh"
-    source "$SCRIPT_DIR/system-detect.sh"
+
+    [ -f "$SCRIPT_DIR/common-functions.sh" ] && source "$SCRIPT_DIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
+    [ -f "$SCRIPT_DIR/system-detect.sh" ] && source "$SCRIPT_DIR/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; return 1; }
 fi
 
 # Source control panel helpers if available

lib/mysql-analyzer.sh

@@ -8,9 +8,10 @@
 # Source dependencies
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$SCRIPT_DIR/common-functions.sh"
-    source "$SCRIPT_DIR/system-detect.sh"
-    source "$SCRIPT_DIR/user-manager.sh"
+
+    [ -f "$SCRIPT_DIR/common-functions.sh" ] && source "$SCRIPT_DIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
+    [ -f "$SCRIPT_DIR/system-detect.sh" ] && source "$SCRIPT_DIR/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; return 1; }
+    [ -f "$SCRIPT_DIR/user-manager.sh" ] && source "$SCRIPT_DIR/user-manager.sh" || { echo "ERROR: user-manager.sh not found" >&2; return 1; }
 fi
 
 #############################################################################

lib/plesk-helpers.sh

@@ -8,7 +8,7 @@
 # Source common functions if not already loaded
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$SCRIPT_DIR/common-functions.sh"
+    [ -f "$SCRIPT_DIR/common-functions.sh" ] && source "$SCRIPT_DIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
 fi
 
 #############################################################################

lib/reference-db.sh

@@ -9,9 +9,10 @@
 # Source dependencies
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$SCRIPT_DIR/common-functions.sh"
-    source "$SCRIPT_DIR/system-detect.sh"
-    source "$SCRIPT_DIR/user-manager.sh"
+
+    [ -f "$SCRIPT_DIR/common-functions.sh" ] && source "$SCRIPT_DIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
+    [ -f "$SCRIPT_DIR/system-detect.sh" ] && source "$SCRIPT_DIR/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; return 1; }
+    [ -f "$SCRIPT_DIR/user-manager.sh" ] && source "$SCRIPT_DIR/user-manager.sh" || { echo "ERROR: user-manager.sh not found" >&2; return 1; }
 fi
 
 # Reference database location

lib/system-detect.sh

@@ -9,7 +9,7 @@
 # Source common functions if not already loaded
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$SCRIPT_DIR/common-functions.sh"
+    [ -f "$SCRIPT_DIR/common-functions.sh" ] && source "$SCRIPT_DIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
 fi
 
 # Global variables (session-only) - only initialize if not already set

lib/user-manager.sh

@@ -8,8 +8,9 @@
 # Source dependencies
 if [ -z "$TOOLKIT_BASE_DIR" ]; then
     _LIB_SRCDIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-    source "$_LIB_SRCDIR/common-functions.sh"
-    source "$_LIB_SRCDIR/system-detect.sh"
+
+    [ -f "$_LIB_SRCDIR/common-functions.sh" ] && source "$_LIB_SRCDIR/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; return 1; }
+    [ -f "$_LIB_SRCDIR/system-detect.sh" ] && source "$_LIB_SRCDIR/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; return 1; }
 fi
 
 # Initialize temp session directory if not set

modules/website/website-error-analyzer.sh

@@ -9,10 +9,11 @@
 ################################################################################
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
-source "$SCRIPT_DIR/lib/common-functions.sh"
-source "$SCRIPT_DIR/lib/system-detect.sh"
-source "$SCRIPT_DIR/lib/user-manager.sh"
-source "$SCRIPT_DIR/lib/ip-reputation.sh"
+
+[ -f "$SCRIPT_DIR/lib/common-functions.sh" ] && source "$SCRIPT_DIR/lib/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; exit 1; }
+[ -f "$SCRIPT_DIR/lib/system-detect.sh" ] && source "$SCRIPT_DIR/lib/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; exit 1; }
+[ -f "$SCRIPT_DIR/lib/user-manager.sh" ] && source "$SCRIPT_DIR/lib/user-manager.sh" || { echo "ERROR: user-manager.sh not found" >&2; exit 1; }
+[ -f "$SCRIPT_DIR/lib/ip-reputation.sh" ] && source "$SCRIPT_DIR/lib/ip-reputation.sh" || { echo "ERROR: ip-reputation.sh not found" >&2; exit 1; }
 
 # Configuration - Use system-detected paths
 APACHE_ERROR_LOG="/var/log/apache2/error_log"  # Will be auto-detected

modules/website/wordpress/wordpress-cron-manager.sh

@@ -12,8 +12,9 @@
 ################################################################################
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../../.." && pwd)"
-source "$SCRIPT_DIR/lib/common-functions.sh"
-source "$SCRIPT_DIR/lib/system-detect.sh"
+
+[ -f "$SCRIPT_DIR/lib/common-functions.sh" ] && source "$SCRIPT_DIR/lib/common-functions.sh" || { echo "ERROR: common-functions.sh not found" >&2; exit 1; }
+[ -f "$SCRIPT_DIR/lib/system-detect.sh" ] && source "$SCRIPT_DIR/lib/system-detect.sh" || { echo "ERROR: system-detect.sh not found" >&2; exit 1; }
 
 if [ "$EUID" -ne 0 ]; then
     print_error "This script must be run as root"