Skip unknown opcode blocks while parsing

src/serialization/sb2.js

@@ -133,17 +133,20 @@ const parseBlockList = function (blockList, addBroadcastMsg, getVariableId, exte
         // eslint-disable-next-line no-use-before-define
         const parsedBlockAndComments = parseBlock(block, addBroadcastMsg, getVariableId,
             extensions, comments, commentIndex);
-        const parsedBlock = parsedBlockAndComments[0];
-        // Update commentIndex
-        commentIndex = parsedBlockAndComments[1];
 
-        if (typeof parsedBlock === 'undefined') continue;
-        if (previousBlock) {
-            parsedBlock.parent = previousBlock.id;
-            previousBlock.next = parsedBlock.id;
+        if (parsedBlockAndComments) { // Could fail due to unrecognized op-codes
+            const parsedBlock = parsedBlockAndComments[0];
+            // Update commentIndex
+            commentIndex = parsedBlockAndComments[1];
+
+            if (typeof parsedBlock === 'undefined') continue;
+            if (previousBlock) {
+                parsedBlock.parent = previousBlock.id;
+                previousBlock.next = parsedBlock.id;
+            }
+            previousBlock = parsedBlock;
+            resultingList.push(parsedBlock);
         }
-        previousBlock = parsedBlock;
-        resultingList.push(parsedBlock);
     }
     return [resultingList, commentIndex];
 };

test/integration/unknown-opcode.js

@@ -0,0 +1,37 @@
+const path = require('path');
+const test = require('tap').test;
+const makeTestStorage = require('../fixtures/make-test-storage');
+const readFileToBuffer = require('../fixtures/readProjectFile').readFileToBuffer;
+const VirtualMachine = require('../../src/index');
+
+const uri = path.resolve(__dirname, '../fixtures/unknown-opcode.sb2');
+const project = readFileToBuffer(uri);
+
+test('unknown opcode', t => {
+    const vm = new VirtualMachine();
+    vm.attachStorage(makeTestStorage());
+
+    vm.start();
+    vm.clear();
+    vm.setCompatibilityMode(false);
+    vm.setTurboMode(false);
+    vm.loadProject(project).then(() => {
+        vm.greenFlag();
+
+        // The project has 3 blocks in a single stack:
+        //      play sound => "undefined" => play sound
+        // the "undefined" block has opcode "0" and was found in the wild.
+        // It should be parsed in without error and it should bridge together
+        // the two play sound blocks, so there should not be a third block.
+        const blocks = vm.runtime.targets[0].blocks;
+        const topBlockId = blocks.getScripts()[0];
+        const secondBlockId = blocks.getNextBlock(topBlockId);
+        const thirdBlockId = blocks.getNextBlock(secondBlockId);
+
+        t.equal(blocks.getBlock(topBlockId).opcode, 'sound_play');
+        t.equal(blocks.getBlock(secondBlockId).opcode, 'sound_play');
+        t.equal(thirdBlockId, null);
+        t.end();
+        process.nextTick(process.exit);
+    });
+});