From ffe828aabe0be033581c5650007e5e7c646ced34 Mon Sep 17 00:00:00 2001
From: Klaas Dannen <dannen@metratec.com>
Date: Fri, 13 Mar 2026 16:07:01 +0100
Subject: [PATCH] Replace assert() with proper exceptions for release-mode
 safety

assert() statements are stripped in Dart release builds, meaning all
NDEF flag validation (MB, ME, CF) and TNF/type-length checks silently
disappear in production. Replaced with FormatException for malformed
NDEF data and RangeError for invalid TNF values, so errors are caught
regardless of build mode.
---
 lib/ndef.dart   | 16 ++++++++++++----
 lib/record.dart | 20 +++++++++++++-------
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/lib/ndef.dart b/lib/ndef.dart
index e39e1be..6c57670 100644
--- a/lib/ndef.dart
+++ b/lib/ndef.dart
@@ -39,14 +39,22 @@ List<NDEFRecord> decodeRawNdefMessage(
   while (!stream.isEnd()) {
     var record = NDEFRecord.decodeStream(stream, typeFactory);
     if (records.isEmpty) {
-      assert(record.flags.MB == true, "MB flag is not set in first record");
+      if (record.flags.MB != true) {
+        throw FormatException("MB flag is not set in first record");
+      }
     } else {
-      assert(record.flags.MB == false, "MB flag is set in middle record");
+      if (record.flags.MB != false) {
+        throw FormatException("MB flag is set in middle record");
+      }
     }
     records.add(record);
   }
-  assert(records.last.flags.ME == true, "ME flag is not set in last record");
-  assert(records.last.flags.CF == false, "CF flag is set in last record");
+  if (records.last.flags.ME != true) {
+    throw FormatException("ME flag is not set in last record");
+  }
+  if (records.last.flags.CF != false) {
+    throw FormatException("CF flag is set in last record");
+  }
   return records;
 }
 
diff --git a/lib/record.dart b/lib/record.dart
index 7fa87a7..8f4bd77 100644
--- a/lib/record.dart
+++ b/lib/record.dart
@@ -37,7 +37,9 @@ class NDEFRecordFlags {
 
   /// Encodes the flags into a single byte.
   int encode() {
-    assert(0 <= TNF && TNF <= 7);
+    if (TNF < 0 || TNF > 7) {
+      throw RangeError.range(TNF, 0, 7, "TNF");
+    }
     return (MB.toInt() << 7) |
         (ME.toInt() << 6) |
         (CF.toInt() << 5) |
@@ -336,15 +338,19 @@ class NDEFRecord {
       idLength = stream.readByte();
     }
 
-    if ([0, 5, 6].contains(flags.TNF)) {
-      assert(typeLength == 0, "TYPE_LENGTH must be 0 when TNF is 0,5,6");
+    if ([0, 5, 6].contains(flags.TNF) && typeLength != 0) {
+      throw FormatException("TYPE_LENGTH must be 0 when TNF is 0,5,6");
     }
     if (flags.TNF == 0) {
-      assert(idLength == 0, "ID_LENGTH must be 0 when TNF is 0");
-      assert(payloadLength == 0, "PAYLOAD_LENGTH must be 0 when TNF is 0");
+      if (idLength != 0) {
+        throw FormatException("ID_LENGTH must be 0 when TNF is 0");
+      }
+      if (payloadLength != 0) {
+        throw FormatException("PAYLOAD_LENGTH must be 0 when TNF is 0");
+      }
     }
-    if ([1, 2, 3, 4].contains(flags.TNF)) {
-      assert(typeLength > 0, "TYPE_LENGTH must be > 0 when TNF is 1,2,3,4");
+    if ([1, 2, 3, 4].contains(flags.TNF) && typeLength <= 0) {
+      throw FormatException("TYPE_LENGTH must be > 0 when TNF is 1,2,3,4");
     }
 
     var type = stream.readBytes(typeLength);