Unclear error message (StringIndexOutOfBoundsException) when passing empty argument to --driver

[arotenberg-google]

Calling the dumper with --driver "" (e.g. due to a bad environment variable on the command line) throws an exception like:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 0
    at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:47)
    at java.base/java.lang.String.charAt(String.java:693)
    at com.google.edwmigration.dumper.application.dumper.JsonResponseFile.addResponseFiles(JsonResponseFile.java:61)
    at com.google.edwmigration.dumper.application.dumper.MetadataDumper.main(MetadataDumper.java:319)

This error message is unclear what the problem is, making it hard for the user to debug.

[vladislav-sidorovich]

Currently error message is different, but the main idea of the issue is still valid.

[vladislav-sidorovich]

fixed at #579