Eclipse Plugin bug - An internal error occurred during: "Refresh Action Items"

As long as no value is defined for the "Server URL" parameter of the Eclipse plugin "collaborator_eclipse_plugin_13_6_13601_java_8.zip" two errors "An internal error occurred during: "Refresh Action Items"." will be shown at the start of Eclipse. The log window of Eclipse gives the following information:

Stack trace:

java.lang.NullPointerException
at com.smartbear.collaborator.json.utils.BatchRequest.<init>(BatchRequest.java:148)
at com.smartbear.collaborator.json.api.AbstractApi.createBatchRequest(AbstractApi.java:50)
at com.smartbear.collaborator.json.api.UserApi.getClientActionItems(UserApi.java:64)
at com.smartbear.collaborator.JsonAPIHandler.getClientActionItems(JsonAPIHandler.java:363)
at com.smartbear.collaborator.ui.ide.jobs.ClientActionItemsRefreshJob.loadActionItems(ClientActionItemsRefreshJob.java:62)
at com.smartbear.collaborator.jobs.AbstractActionItemsRefreshJob.doRun(AbstractActionItemsRefreshJob.java:46)
at com.smartbear.collaborator.ui.ide.jobs.ClientActionItemsRefreshJob.doRun(ClientActionItemsRefreshJob.java:72)
at com.smartbear.collaborator.jobs.RefreshJob.run(RefreshJob.java:95)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:56)

Expected:

If no value for the "Server URL" parameter is defined, the Eclipse plugin should deal with this (maybe via a warning?) instead of causing a NullPointerException.