another try

Author: ctzsnooze

src/js/msp/MSPHelper.js

@@ -2456,7 +2456,6 @@ MspHelper.prototype.dataflashRead = function(address, blockSize, onDataCallback)
         1 // allow compression
     ];
 
-    // Ensure MSP object exists
     const mspObj = this.msp || (typeof MSP !== 'undefined' ? MSP : null);
     if (!mspObj) {
         console.error('MSP object not found, cannot read dataflash.');
@@ -2465,29 +2464,35 @@ MspHelper.prototype.dataflashRead = function(address, blockSize, onDataCallback)
     }
 
     mspObj.send_message(MSPCodes.MSP_DATAFLASH_READ, outData, false, function(response) {
-        const headerSize = 7;
-        const chunkAddress = response.data.readU32();
-        const dataSize = response.data.readU16();
-        const dataCompressionType = response.data.readU8();
-
-        let payloadView;
-        if (dataCompressionType === 0) {
-            payloadView = new DataView(response.data.buffer, response.data.byteOffset + headerSize, dataSize);
-        } else if (dataCompressionType === 1) {
-            const compressedCharCount = response.data.readU16();
-            const compressedArray = new Uint8Array(response.data.buffer, response.data.byteOffset + headerSize + 2, dataSize - 2);
-            const decompressedArray = huffmanDecodeBuf(compressedArray, compressedCharCount, defaultHuffmanTree, defaultHuffmanLenIndex);
-            payloadView = new DataView(decompressedArray.buffer);
+        let payloadView = null;
+
+        if (response && response.data) {
+            const headerSize = 7;
+            const chunkAddress = response.data.readU32();
+            const dataSize = response.data.readU16();
+            const dataCompressionType = response.data.readU8();
+
+            if (chunkAddress === address) {
+                if (dataCompressionType === 0) {
+                    payloadView = new DataView(response.data.buffer, response.data.byteOffset + headerSize, dataSize);
+                } else if (dataCompressionType === 1) {
+                    const compressedCharCount = response.data.readU16();
+                    const compressedArray = new Uint8Array(response.data.buffer, response.data.byteOffset + headerSize + 2, dataSize - 2);
+                    const decompressedArray = huffmanDecodeBuf(compressedArray, compressedCharCount, defaultHuffmanTree, defaultHuffmanLenIndex);
+                    payloadView = new DataView(decompressedArray.buffer);
+                }
+            } else {
+                console.log(`Expected address ${address} but received ${chunkAddress}`);
+            }
         }
 
-        // Always deliver data, even if CRC fails
+        // Deliver payloadView if defined, otherwise pass null
         onDataCallback(address, payloadView);
-        if (response.crcError) {
-            console.log(`CRC error for block at ${address} ignored; data delivered`);
-        } else if (chunkAddress !== address) {
-            console.log(`Expected address ${address} but received ${chunkAddress}`);
-        } else {
-            console.log(`Block at ${address} received (${dataSize} bytes)`);
+
+        if (!response || response.crcError) {
+            console.log(`CRC error or missing data at address ${address} - delivering whatever we got`);
+        } else if (payloadView) {
+            console.log(`Block at ${address} received (${payloadView.byteLength} bytes)`);
         }
     }, true);
 };