void cleanup() {
		this.program = null;
		extLibNameComboBox.removeDocumentListener(nameDocumentListener);
		nameDocumentListener = null;
		extLibNameComboBox.removeItemListener(nameItemListener);
		nameItemListener = null;
		this.externalLocation = null;
		this.startingExternalLibraryName = null;
		this.startingLocationName = null;
		this.startingLocationAddress = null;
		this.autoDeterminedExternalLibraryPath = null;
	}
Display input error
@param error error message
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/symboltree/EditExternalLocationPanel.java