Do not remove recent file entries when they are not found

[richlv]

What steps will reproduce the problem?

1. Open a file from a removable device, close the file.
2. Remove the device.
3. Choose the same file from "File -> Open Recent".

What is the expected result?

Error, but entry kept (to be used when the device is reinserted).

What happens instead?

Recent file entry is removed.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-09-03 03:12:33 +0200 (Fri, 03 Sep 2021)
Build-Date:2021-09-03 01:31:19
Revision:18193
Relative:URL: ^/trunk

Identification: JOSM/1.5 (18193 en_GB) Mac OS X 10.15.7
OS Build number: Mac OS X 10.15.7 (19H1419)
Memory Usage: 1695 MB / 3641 MB (334 MB allocated, but free)
Java version: 1.8.0_301-b09, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 69733382 1680×1050 (scaling 1.00×1.00)
Maximum Screen Size: 1680×1050
Best cursor sizes: 16×16→16×16, 32×32→32×32
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_GB
Numbers with default locale: 1234567890 -> 1234567890
VM arguments: [-Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlp.tk=awt, -Djnlpx.jvm=<java.home>/bin/java, -Djnlpx.splashport=-1, -Djnlpx.home=<java.home>/bin, -Djnlpx.remove=false, -Djnlpx.offline=false, -Djnlpx.relaunch=true, -Djnlpx.session.data=/var/folders/nl/flqxqsmj5q963r7tcnfrdt3c0000gn/T/session3422512052515284784, -Djnlpx.heapsize=NULL,NULL, -Djava.security.policy=file:<java.home>/lib/security/javaws.policy, -DtrustProxy=true, -Djnlpx.origFilenameArg=/Users/richlv/Library/Application Support/Oracle/Java/Deployment/cache/6.0/56/1ee8cfb8-72e8e992, -Dsun.awt.warmup=true, -Djava.security.manager]

Plugins:
+ HouseNumberTaggingTool (35814)
+ InfoMode (35543)
+ Mapillary (2.0.0-alpha.36-dirty)
+ PicLayer (1.0.1)
+ apache-commons (35524)
+ apache-http (35589)
+ buildings_tools (35823)
+ dataimport (35640)
+ ejml (35458)
+ geotools (35458)
+ imagery_offset_db (35640)
+ jaxb (35543)
+ jna (35662)
+ jts (35458)
+ measurement (35640)
+ opendata (35803)
+ pbf (35825)
+ photo_geotagging (35783)
+ reverter (35732)
+ utilsplugin2 (35792)

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&zip=1

Last errors/warnings:
- 01682.069 W: java.net.SocketTimeoutException: connect timed out
- 01691.547 W: java.net.SocketTimeoutException: connect timed out
- 01691.572 W: java.net.SocketTimeoutException: connect timed out
- 01691.572 W: java.net.SocketTimeoutException: connect timed out
- 01691.573 W: Already here java.net.SocketTimeoutException: connect timed out
- 01697.150 W: java.net.SocketTimeoutException: connect timed out
- 01697.150 W: java.net.SocketTimeoutException: connect timed out
- 01697.151 W: Already here java.net.SocketTimeoutException: connect timed out
- 01697.152 W: java.net.SocketTimeoutException: connect timed out
- 01697.153 W: Already here java.net.SocketTimeoutException: connect timed out

[skyper]

If changing this, can we please have it optional. I like the removal and wonder why it does not work with *.jos and *.joz.