Make sure that unregistered event sources do not stop JabRef from shu…

CHANGELOG.md

@@ -24,7 +24,8 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - The [ACM fetcher](https://help.jabref.org/en/ACMPortal) does no longer add HTML code to the bib-file. Fixes [#2472](https://github.com/JabRef/jabref/issues/2472).
 - When [finding unlinked files](https://help.jabref.org/en/FindUnlinkedFiles), JabRef does not freeze any more. Fixes [#2309]()https://github.com/JabRef/jabref/issues/2309).
 - Collapse and expand all buttons in the group assignment dialog no longer lead to a crash of JabRef.
-- The aux export command line function does no longer add duplicates of references that were resolved via `crossref`. Fixes [#2475](https://github.com/JabRef/jabref/issues/2475). 
+- The aux export command line function does no longer add duplicates of references that were resolved via `crossref`. Fixes [#2475](https://github.com/JabRef/jabref/issues/2475).
+- When the database is changed external, JabRef is no longer prevented from an orderly shutdown. Fixes [#2486](https://github.com/JabRef/jabref/issues/2486).
 - Parsing of damaged metadata is now more robust and reports a more detailed error message. Fixes [#2477](https://github.com/JabRef/jabref/issues/2477).
 - Dynamic groups with regular expression can be edited again. Fixes [#2481](https://github.com/JabRef/jabref/issues/2481).
 

src/main/java/net/sf/jabref/logic/autosaveandbackup/AutosaveManager.java

@@ -89,6 +89,11 @@ public void registerListener(Object listener) {
     }
 
     public void unregisterListener(Object listener) {
-        eventBus.unregister(listener);
+        try {
+            eventBus.unregister(listener);
+        } catch (IllegalArgumentException e) {
+            // occurs if the event source has not been registered, should not prevent shutdown
+            LOGGER.debug(e);
+        }
     }
 }

src/main/java/net/sf/jabref/logic/search/SearchQueryHighlightObservable.java

@@ -31,7 +31,11 @@ public void addSearchListener(SearchQueryHighlightListener newListener) {
     public void removeSearchListener(SearchQueryHighlightListener listener) {
         Objects.requireNonNull(listener);
 
-        eventBus.unregister(listener);
+        try {
+            eventBus.unregister(listener);
+        } catch (IllegalArgumentException e) {
+            // occurs if the event source has not been registered, should not prevent shutdown
+        }
     }
     /**
      * Fires an event if a search was started (or cleared)

src/main/java/net/sf/jabref/model/database/BibDatabase.java

@@ -530,7 +530,12 @@ public void registerListener(Object listener) {
      * @param listener listener (subscriber) to remove
      */
     public void unregisterListener(Object listener) {
-        this.eventBus.unregister(listener);
+        try {
+            this.eventBus.unregister(listener);
+        } catch (IllegalArgumentException e) {
+            // occurs if the event source has not been registered, should not prevent shutdown
+            LOGGER.debug(e);
+        }
     }
 
     @Subscribe

src/main/java/net/sf/jabref/model/entry/BibEntry.java

@@ -764,7 +764,12 @@ public void registerListener(Object object) {
     }
 
     public void unregisterListener(Object object) {
-        this.eventBus.unregister(object);
+        try {
+            this.eventBus.unregister(object);
+        } catch (IllegalArgumentException e) {
+            // occurs if the event source has not been registered, should not prevent shutdown
+            LOGGER.debug(e);
+        }
     }
 
     public BibEntry withField(String field, String value) {

src/main/java/net/sf/jabref/model/metadata/MetaData.java

@@ -254,7 +254,11 @@ public void registerListener(Object listener) {
     }
 
     public void unregisterListener(Object listener) {
-        this.eventBus.unregister(listener);
+        try {
+            this.eventBus.unregister(listener);
+        } catch (IllegalArgumentException e) {
+            // occurs if the event source has not been registered, should not prevent shutdown
+        }
     }
 
     private Optional<String> getDefaultCiteKeyPattern() {