Error popup appears for projects without ROS Path

[Noam-Dori]

Describe the bug
Error popup appears for projects without ROS Path

To Reproduce
Steps to reproduce the behavior:

1. Open a project
2. In the ROS settings, make sure the "ROS Path" variable is empty
3. A log error popup appears with the stack trace

Expected behavior
The popup should not appear at all

Environment Information:

• OS: Ubuntu 20.04
• IDE: CLion 2020.2
• Plugin Version: 0.1.6
• Related Plugins: none

Stack Trace
java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
at ros.integrate.pkg.ROSCompiledPackageFinder.getROSRoot(ROSCompiledPackageFinder.java:49)
at ros.integrate.pkg.ROSCompiledPackageFinder.inFinder(ROSCompiledPackageFinder.java:134)
at ros.integrate.pkg.ROSPackageFinderBase.lambda$investigate$1(ROSPackageFinderBase.java:98)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:176)
at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
at ros.integrate.pkg.ROSPackageFinderBase.investigate(ROSPackageFinderBase.java:101)
at ros.integrate.pkg.ROSPackageManagerImpl.lambda$applyChangesToOrphans$3(ROSPackageManagerImpl.java:96)
at com.intellij.openapi.application.TransactionGuardImpl$2.run(TransactionGuardImpl.java:201)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:802)
at com.intellij.openapi.application.impl.ApplicationImpl.lambda$invokeLater$4(ApplicationImpl.java:322)
at com.intellij.openapi.application.impl.FlushQueue.doRun(FlushQueue.java:84)
at com.intellij.openapi.application.impl.FlushQueue.runNextEvent(FlushQueue.java:132)
at com.intellij.openapi.application.impl.FlushQueue.flushNow(FlushQueue.java:47)
at com.intellij.openapi.application.impl.FlushQueue$FlushNow.run(FlushQueue.java:188)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:313)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:776)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:746)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:971)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:841)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$8(IdeEventQueue.java:452)
at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:744)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$9(IdeEventQueue.java:451)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:802)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:499)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)=