Verifies material exists on server and if not supplies AIR.

https://github.com/BentoBoxWorld/BentoBox/issues/1037

src/main/java/world/bentobox/bentobox/database/json/adapters/ItemStackTypeAdapter.java

@@ -2,6 +2,7 @@ package world.bentobox.bentobox.database.json.adapters;
 
 import java.io.IOException;
 
+import org.bukkit.Material;
 import org.bukkit.configuration.InvalidConfigurationException;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.bukkit.inventory.ItemStack;
@@ -11,6 +12,8 @@ import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
 
+import world.bentobox.bentobox.BentoBox;
+
 /**
  * Serializes ItemStack to JSON and back.
  * I'm going to cheat and use Bukkit's built in YAML serializer/deserializer.
@@ -38,11 +41,24 @@ public class ItemStackTypeAdapter extends TypeAdapter<ItemStack> {
             return null;
         }
         YamlConfiguration c = new YamlConfiguration();
+        String n = reader.nextString();
+        // Verify material type because yaml loading errors of unknown materials cannot be trapped bu try clause.
+        if (n.contains("type:")) {
+            String type = n.substring(n.indexOf("type:") + 6, n.length());
+            type = type.substring(0, type.indexOf("\n"));
+            Material m = Material.matchMaterial(type);            
+            if (m == null) {
+                BentoBox.getInstance().logWarning("Unknown material: " + type);
+                return new ItemStack(Material.AIR);
+            }
+
+        }
         try {
-            c.loadFromString(reader.nextString());
+            c.loadFromString(n);
             return c.getItemStack("is");
         } catch (InvalidConfigurationException e) {
-            throw new IOException(e.getMessage());
+            BentoBox.getInstance().logError("Cannot load ItemStack serialized as " + n);
+            return new ItemStack(Material.AIR);
         }
     }
 

src/test/java/world/bentobox/bentobox/database/json/adapters/ItemStackTypeAdapterTest.java

@@ -3,6 +3,7 @@ package world.bentobox.bentobox.database.json.adapters;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -33,11 +34,14 @@ import org.mockito.Mockito;
 import org.powermock.api.mockito.PowerMockito;
 import org.powermock.core.classloader.annotations.PrepareForTest;
 import org.powermock.modules.junit4.PowerMockRunner;
+import org.powermock.reflect.Whitebox;
 
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
 
+import world.bentobox.bentobox.BentoBox;
+
 /**
  * Tests the ItemStack type adapter for GSON
  * @author tastybento
@@ -47,9 +51,13 @@ import com.google.gson.stream.JsonWriter;
 @RunWith(PowerMockRunner.class)
 @PrepareForTest( {Bukkit.class, ItemStack.class} )
 public class ItemStackTypeAdapterTest {
-
+    @Mock
+    private BentoBox plugin;
+    
     private ItemStackTypeAdapter isa;
+    @Mock
     private JsonWriter out;
+    @Mock
     private JsonReader reader;
     @Mock
     private ItemFactory itemFactory;
@@ -59,6 +67,10 @@ public class ItemStackTypeAdapterTest {
      */
     @Before
     public void setUp() throws Exception {
+     // Set up plugin
+        plugin = mock(BentoBox.class);
+        Whitebox.setInternalState(BentoBox.class, "instance", plugin);
+        
         Server server = mock(Server.class);
 
         PluginManager pim = mock(PluginManager.class);
@@ -76,8 +88,8 @@ public class ItemStackTypeAdapterTest {
         when(unsafe.getDataVersion()).thenReturn(777);
         when(Bukkit.getUnsafe()).thenReturn(unsafe);
         isa = new ItemStackTypeAdapter();
-        out = mock(JsonWriter.class);
-        reader = mock(JsonReader.class);
+
+        // Resder
         when(reader.peek()).thenReturn(JsonToken.STRING);
 
         // Mock up the deserialization
@@ -143,5 +155,32 @@ public class ItemStackTypeAdapterTest {
         // Delete temp file
         Files.deleteIfExists(tmp.toPath());
     }
+    
+    /**
+     * Test method for {@link world.bentobox.bentobox.database.json.adapters.ItemStackTypeAdapter#read(com.google.gson.stream.JsonReader)}.
+     * @throws IOException
+     */
+    @Test
+    public void testReadJsonReaderUnknownMaterial() throws IOException {
+        File tmp = new File("test.json");
+        // Write a file - skip the meta because it causes the reader to choke if the class mentioned isn't known
+        try (FileWriter writer = new FileWriter(tmp.getName());
+                Writer buffWriter = new BufferedWriter(writer);
+                JsonWriter realOut = new JsonWriter(buffWriter)) {
+            realOut.value("is:\n  ==: org.bukkit.inventory.ItemStack\n  v: 777\n  type: UNOBTANIUM\n  amount: 4\n");
+            realOut.flush();
+        }
+        // Read it back
+        try (FileReader reader = new FileReader(tmp.getName());
+                Reader buffReader = new BufferedReader(reader);
+                JsonReader realIn = new JsonReader(buffReader)) {
+            ItemStack i = isa.read(realIn);
+            assertEquals(Material.AIR, i.getType());
+            assertEquals(1, i.getAmount());
+            verify(plugin).logWarning(eq("Unknown material: UNOBTANIUM"));
+        }
+        // Delete temp file
+        Files.deleteIfExists(tmp.toPath());
+    }
 
 }