JabRef version:
JabRef 5.0--2020-03-06--2e6f433
Linux 4.18.19-100.fc27.x86_64 amd64
Java 13.0.2

This error fires each time I push a key in the "author" field.

Detalis:

java.lang.ClassCastException: class java.lang.String cannot be cast to class org.jabref.model.entry.Author (java.lang.String is in module java.base of loader 'bootstrap'; org.jabref.model.entry.Author is in module org.jabref of loader 'app')
at org.jabref/org.jabref.gui.autocompleter.PersonNameStringConverter.toString(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.cell.CellUtils.getItemText(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.cell.CellUtils.updateItem(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.cell.TextFieldListCell.updateItem(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.ListCell.updateItem(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.ListCell.indexChanged(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.IndexedCell.updateIndex(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.skin.VirtualFlow.setCellIndex(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.skin.VirtualFlow.getCell(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.skin.VirtualFlow.getCellLength(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.skin.VirtualFlow.computeViewportOffset(Unknown Source)
at org.jabref.merged.module/javafx.scene.control.skin.VirtualFlow.layoutChildren(Unknown Source)
at org.jabref.merged.module/javafx.scene.Parent.layout(Unknown Source)
at org.jabref.merged.module/javafx.scene.Parent.layout(Unknown Source)
at org.jabref.merged.module/javafx.scene.Parent.layout(Unknown Source)
at org.jabref.merged.module/javafx.scene.Parent.layout(Unknown Source)
at org.jabref.merged.module/javafx.scene.Scene.doLayoutPass(Unknown Source)
at org.jabref.merged.module/javafx.scene.Scene$2$1.doLayoutPass(Unknown Source)
at org.jabref.merged.module/javafx.scene.Scene.preferredSize(Unknown Source)
at org.jabref.merged.module/javafx.scene.Scene$2.preferredSize(Unknown Source)
at org.jabref.merged.module/com.sun.javafx.scene.SceneHelper.preferredSize(Unknown Source)
at org.jabref.merged.module/javafx.stage.Window$12.invalidated(Unknown Source)
at org.jabref.merged.module/javafx.beans.property.BooleanPropertyBase.markInvalid(Unknown Source)
at org.jabref.merged.module/javafx.beans.property.BooleanPropertyBase.set(Unknown Source)
at org.jabref.merged.module/javafx.stage.Window.setShowing(Unknown Source)
at org.jabref.merged.module/javafx.stage.Window.show(Unknown Source)
at org.jabref.merged.module/javafx.stage.PopupWindow.showImpl(Unknown Source)
at org.jabref.merged.module/javafx.stage.PopupWindow.show(Unknown Source)
at org.jabref.merged.module/impl.org.controlsfx.skin.AutoCompletePopup.show(Unknown Source)
at org.jabref.merged.module/org.controlsfx.control.textfield.AutoCompletionBinding.showPopup(Unknown Source)
at org.jabref.merged.module/org.controlsfx.control.textfield.AutoCompletionBinding$FetchSuggestionsTask.lambda$call$0(Unknown Source)
at org.jabref.merged.module/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(Unknown Source)
at java.base/java.security.AccessController.doPrivileged(Unknown Source)
at org.jabref.merged.module/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(Unknown Source)
at org.jabref.merged.module/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
at org.jabref.merged.module/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at org.jabref.merged.module/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$11(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)