java.lang.NullPointerException
        at java.io.File.<init>(File.java:222)
        at org.netbeans.modules.ruby.platform.gems.GemRunner.runGemTool(GemRunner.java:332)
        at org.netbeans.modules.ruby.platform.gems.GemRunner.access$100(GemRunner.java:75)
        at org.netbeans.modules.ruby.platform.gems.GemRunner$2.run(GemRunner.java:510)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)