Provide better error message while parsing js files

[Plamen5kov]

problem
When, for some reason, CLI doesn't manage to transpile and move the js files correctly inside platforms/android/src/main/assets/app and it's left empty the following runtime error occurs:

Exception in thread "main" java.io.FileNotFoundException: D:\Work\master\network-agent-master\platforms\android\build-tools\android-static-binding-generator\bindings.txt (The system cannot find the file specified)
       at java.io.FileInputStream.open0(Native Method)
       at java.io.FileInputStream.open(FileInputStream.java:195)
       at java.io.FileInputStream.<init>(FileInputStream.java:138)
       at java.io.FileInputStream.<init>(FileInputStream.java:93)
       at org.nativescript.staticbindinggenerator.Generator.getRows(Generator.java:132)
       at org.nativescript.staticbindinggenerator.Generator.generateBindings(Generator.java:75)
       at org.nativescript.staticbindinggenerator.Generator.writeBindings(Generator.java:54)
       at org.nativescript.staticbindinggenerator.Main.main(Main.java:15)
:asbg:generateBindings FAILED

That means the js_parser didn't find any js files to pars and didn't generate <proj_name>/platforms/android/build-tools/android-static-binding-generator/bindings.txt

how to reproduce

tns create tsproject --tsc
tns create jsproject
rm -rf jsproject/app
cp -r tsproject/app jsproject
cd jsproject
tns platform add android@3.2.0
tns run android

// to check the fixed version do:
tns platform remove android
tns platform add android@next
tns run android

solution
Provide a better error message during the project build.