fix[purpur]: use mc-image-helper for robust Purpur build lookup (#1242)

scripts/start-deployPurpur

@@ -2,7 +2,8 @@
 set -euo pipefail
 IFS=$'\n\t'
 
-. ${SCRIPTS:-/}start-utils
+# shellcheck source=start-utils
+. "${SCRIPTS:-/}start-utils"
 isDebugging && set -x
 
 : ${VANILLA_VERSION:?}
@@ -10,12 +11,10 @@ isDebugging && set -x
 : ${FORCE_REDOWNLOAD:=false}
 
 if [[ ${PURPUR_BUILD} == LATEST ]]; then
-  PURPUR_BUILD=$(curl -fsSL "https://api.purpurmc.org/v2/purpur/${VANILLA_VERSION}" |
-    jq -r '.builds.latest' || echo "")
-  if [[ -z ${PURPUR_BUILD} ]]; then
+  if ! PURPUR_BUILD=$(get --json-path=".builds.latest" "https://api.purpurmc.org/v2/purpur/${VANILLA_VERSION}"); then
     log "ERROR: Failed to locate a Purpur build for ${VANILLA_VERSION}."
     log "       Please check if a download is available at https://purpur.pl3x.net/downloads/"
-    exit 3
+    exit 1
   fi
 fi
 
@@ -24,7 +23,7 @@ export SERVER="purpur-${VANILLA_VERSION}-${PURPUR_BUILD}.jar"
 if [ ! -f "$SERVER" ] || isTrue "$FORCE_REDOWNLOAD"; then
     downloadUrl="https://api.purpurmc.org/v2/purpur/${VANILLA_VERSION}/${PURPUR_BUILD}/download"
     log "Downloading Purpur from $downloadUrl ..."
-    if ! curl -fsSL -o "$SERVER" "$downloadUrl"; then
+    if ! get -o "$SERVER" "$downloadUrl"; then
       log "ERROR: failed to download from $downloadUrl (status=$?)"
       exit 3
     fi
@@ -35,4 +34,4 @@ export TYPE=SPIGOT
 export FAMILY=SPIGOT
 export SKIP_LOG4J_CONFIG=true
 
-exec ${SCRIPTS:-/}start-spiget "$@"
+exec "${SCRIPTS:-/}start-spiget" "$@"