Fix set -e compatibility in lib functions

- Replace [[ ]] && error pattern with if/then/fi
- Pattern causes exit when condition is false with set -e
- Fixed in: common.sh, config.sh, disk.sh, install-archzfs

Discovered during VM testing: the && short-circuit returns exit
code 1 when condition is false, triggering set -e to abort.

3 files changed, 9 insertions, 3 deletions

diff --git a/custom/lib/common.sh b/custom/lib/common.sh
index a41441d..2f8844e 100644
--- a/custom/lib/common.sh
+++ b/custom/lib/common.sh
@@ -42,7 +42,9 @@ log() {
 #############################
 
 require_root() {
-    [[ $EUID -ne 0 ]] && error "This script must be run as root"
+    if [[ $EUID -ne 0 ]]; then
+        error "This script must be run as root"
+    fi
 }
 
 command_exists() {
diff --git a/custom/lib/config.sh b/custom/lib/config.sh
index 82f5d77..cec3d8c 100644
--- a/custom/lib/config.sh
+++ b/custom/lib/config.sh
@@ -122,6 +122,8 @@ validate_config() {
         ((errors++))
     fi
 
-    [[ $errors -gt 0 ]] && error "Config validation failed with $errors error(s)"
+    if [[ $errors -gt 0 ]]; then
+        error "Config validation failed with $errors error(s)"
+    fi
     info "Config validation passed"
 }
diff --git a/custom/lib/disk.sh b/custom/lib/disk.sh
index ea8c402..fa3dbd2 100644
--- a/custom/lib/disk.sh
+++ b/custom/lib/disk.sh
@@ -148,7 +148,9 @@ select_disks() {
         read -rp "Enter disk path(s) separated by space: " selected
     fi
 
-    [[ -z "$selected" ]] && error "No disk selected"
+    if [[ -z "$selected" ]]; then
+        error "No disk selected"
+    fi
 
     # Extract just the device paths (remove size/model info)
     SELECTED_DISKS=()