Fix JDK count variable initialization in setup_java (#9058)

Author: MickLesk

misc/tools.func

@@ -2787,8 +2787,9 @@ function setup_java() {
   fi
 
   # Validate INSTALLED_VERSION is not empty if matched
-  local JDK_COUNT=$(dpkg -l 2>/dev/null | grep -c "temurin-.*-jdk" || echo "0")
-  if [[ -z "$INSTALLED_VERSION" && "$JDK_COUNT" -gt 0 ]]; then
+  local JDK_COUNT=0
+  JDK_COUNT=$(dpkg -l 2>/dev/null | grep -c "temurin-.*-jdk" || echo "0")
+  if [[ -z "$INSTALLED_VERSION" && "${JDK_COUNT:-0}" -gt 0 ]]; then
     msg_warn "Found Temurin JDK but cannot determine version"
     INSTALLED_VERSION="0"
   fi