fix: The provided Android NDK is vnull while the recommended one is v21.0.6113669 error in some cases

Author: DimitarTachev

snapshot/android/snapshot-generator.js

@@ -400,7 +400,11 @@ SnapshotGenerator.prototype.buildCSource = function (androidArch, blobInputDir,
 }
 
 SnapshotGenerator.prototype.getRecommendedNdkWarning=function(localNdkRevision,recommendedAndroidNdkRevision){
-return`The provided Android NDK is v${localNdkRevision} while the recommended one is v${recommendedAndroidNdkRevision}`;
+if(localNdkRevision){
+return`The provided Android NDK is v${localNdkRevision} while the required one is v${recommendedAndroidNdkRevision}`;
+}else{
+return`The provided Android NDK version is different than the required one - v${recommendedAndroidNdkRevision}`;
+}
 }
 
 SnapshotGenerator.prototype.runMksnapshotTool=function(tool,mksnapshotParams,inputFile,snapshotInDocker,snapshotToolsPath,buildCSource){