minor code review of lz4-related code

src/js/lz4.js

@@ -114,6 +114,7 @@ let encodeValue = function(key, value) {
     let inputArray = textEncoder.encode(value);
     let inputSize = inputArray.byteLength;
     let outputArray = lz4CodecInstance.encodeBlock(inputArray, 8);
+    if ( outputArray instanceof Uint8Array === false ) { return; }
     outputArray[0] = 0x18;
     outputArray[1] = 0x4D;
     outputArray[2] = 0x22;
@@ -146,6 +147,7 @@ let decodeValue = function(key, inputArray) {
         (inputArray[4] <<  0) | (inputArray[5] <<  8) |
         (inputArray[6] << 16) | (inputArray[7] << 24);
     let outputArray = lz4CodecInstance.decodeBlock(inputArray, 8, outputSize);
+    if ( outputArray instanceof Uint8Array === false ) { return; }
     if ( textDecoder === undefined ) {
         textDecoder = new TextDecoder();
     }
@@ -173,7 +175,7 @@ return {
             if ( dataOut instanceof Uint8Array ) {
                 dataOut = new Blob([ dataOut ]);
             }
-            return { key, data: dataOut };
+            return { key, data: dataOut || dataIn };
         });
     },
     decode: function(key, dataIn) {

src/lib/lz4/README.md

@@ -20,8 +20,9 @@ If the choosen implementation is not specified, there will be an attempt to
 create a WebAssembly-based instance. If for whatever reason this fails, a
 pure javascript-based instance will be created.
 
-The script for either instance are dynamically loaded, such that no resources
-are wasted by keeping in memory code which won't be used.
+The script for either instance are dynamically loaded and only when needed,
+such that no resources are wasted by keeping in memory code which won't be
+used.
  
 ### `lz4-block-codec-wasm.js`
 

src/lib/lz4/lz4-block-codec-js.js

@@ -64,7 +64,7 @@ let encodeBound = function(size) {
 
 let encodeBlock = function(instance, iBuf, oOffset) {
     let iLen = iBuf.byteLength;
-    if ( iLen >= 0x7E000000 ) { throw new TypeError(); }
+    if ( iLen >= 0x7E000000 ) { throw new RangeError(); }
 
     // "The last match must start at least 12 bytes before end of block"
     let lastMatchPos = iLen - 12;
@@ -216,7 +216,7 @@ let decodeBlock = function(instance, iBuf, iOffset, oLen) {
 
         // match
         let mOffset = iBuf[iPos+0] | (iBuf[iPos+1] << 8);
-        if ( mOffset === 0 || mOffset > oPos ) { return 0; }
+        if ( mOffset === 0 || mOffset > oPos ) { return; }
         iPos += 2;
 
         // length of match

src/lib/lz4/lz4-block-codec-wasm.js

@@ -72,7 +72,7 @@ let encodeBlock = function(wasmInstance, inputArray, outputOffset) {
     let mem0 = lz4api.getLinearMemoryOffset();
     let hashTableSize = 65536 * 4;
     let inputSize = inputArray.byteLength;
-    if ( inputSize >= 0x7E000000 ) { throw new TypeError(); }
+    if ( inputSize >= 0x7E000000 ) { throw new RangeError(); }
     let memSize =
         hashTableSize +
         inputSize +
@@ -87,9 +87,7 @@ let encodeBlock = function(wasmInstance, inputArray, outputOffset) {
         inputSize,
         mem0 + hashTableSize + inputSize + outputOffset
     );
-    if ( outputSize === 0 ) {
-        inputSize = 0 - inputSize;
-    }
+    if ( outputSize === 0 ) { return; }
     let outputArray = new Uint8Array(
         memBuffer,
         mem0 + hashTableSize + inputSize,
@@ -111,9 +109,7 @@ let decodeBlock = function(wasmInstance, inputArray, inputOffset, outputSize) {
         inputSize - inputOffset,
         mem0 + inputSize
     );
-    if ( outputSize === 0 ) {
-        throw new Error('LZ4BlockWASM: block-level compression failed');
-    }
+    if ( outputSize === 0 ) { return; }
     return new Uint8Array(memBuffer, mem0 + inputSize, outputSize);
 };