fix: harden get_version_name against missing file and extraction failures

Made-with: Cursor

build.sh

@@ -35,7 +35,17 @@ warn()    { echo -e "${YELLOW}⚠${NC} $1"; }
 error()   { echo -e "${RED}✗${NC} $1"; }
 
 get_version_name() {
-    grep 'versionName' "$GRADLE_BUILD_FILE" | head -1 | sed 's/.*"\(.*\)".*/\1/'
+    if [[ ! -f "$GRADLE_BUILD_FILE" ]]; then
+        error "Build file not found: $GRADLE_BUILD_FILE"
+        exit 1
+    fi
+    local v
+    v=$(grep 'versionName' "$GRADLE_BUILD_FILE" | head -1 | sed 's/.*"\([^"]*\)".*/\1/')
+    if [[ -z "$v" ]]; then
+        error "Could not extract version from $GRADLE_BUILD_FILE"
+        exit 1
+    fi
+    echo "$v"
 }
 
 preflight_check() {