JOSM freezes with error messages

[jfd553]

What steps will reproduce the problem?

1. Open a session and use imagery (Mapbox)
2. After a while JOSM freezes with blank error messages or messages about memory
3. Must close the application with a task manager

What is the expected result?

I used to work for hours without any problems (same type of edits, same imagery, ...). Fast imagery alignment with gps tracks.

What happens instead?

Since a week or two JOSM seems to be very slow dealing with imagery. Worst symptoms occur when aligning imagery to gps tracks. I have to wait 1-2 minutes sometime to see the image rectified.

Please provide any additional information below. Attach a screenshot if possible.

Error messages, when not blank, concern the amount of memory used. I have set the -Xmx value to 1024 (and even tried 2G). The link I use to start the application begins that way:
"C:\Program Files (x86)\Java\jre1.8.0_31\bin\javaws.exe" -Xmx1024M -localfile ...

I have attached two screenshots of error messages and the status report.
Warning messages below are linked to bad data results caused by the crash of my previous editing session.

Thanks

Revision: 8279
Repository Root: http://josm.openstreetmap.de/svn
Relative URL: ^/trunk
Last Changed Author: Klumbumbus
Last Changed Date: 2015-04-26 22:42:34 +0200 (Sun, 26 Apr 2015)
Build-Date: 2015-04-27 01:31:19
URL: http://josm.openstreetmap.de/svn/trunk
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last Changed Rev: 8279

Identification: JOSM/1.5 (8279 en) Windows 7 64-Bit
Memory Usage: 135 MB / 247 MB (29 MB allocated, but free)
Java version: 1.8.0_31, Oracle Corporation, Java HotSpot(TM) Client VM
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:C:\Program Files (x86)\Java\jre1.8.0_31\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=C:\Users\Daniel\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\56\1ee8cfb8-307b9a02, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.splashport=62205, -Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp, -Djnlpx.jvm=<java.home>\bin\javaw.exe, -Djnlpx.vmargs=LURqYXZhLnV0aWwuQXJyYXlzLnVzZUxlZ2FjeU1lcmdlU29ydD10cnVlAC1Eam5scC5hcHBsaWNhdGlvbi5ocmVmPWh0dHBzOi8vam9zbS5vcGVuc3RyZWV0bWFwLmRlL2Rvd25sb2FkL2pvc20uam5scAA=]

Plugins:
- PicLayer (31114)
- imageryadjust (30892)
- reverter (30990)
- turnrestrictions (31034)

Last errors/warnings:
- E: org.openstreetmap.josm.io.OsmApiException: ResponseCode=412, Error Header=<Precondition failed: Way  requires the nodes with id in (1307340578), which either do not exist, or are not visible.>
- W: java.io.IOException: Server returned HTTP response code: 412 for URL: https://api.openstreetmap.org/api/0.6/changeset/30813154/upload. Cause: java.io.IOException: Server returned HTTP response code: 412 for URL: https://api.openstreetmap.org/api/0.6/changeset/30813154/upload
- E: Error header: Precondition failed: Way  requires the nodes with id in (1307340578), which either do not exist, or are not visible.
- W: Error header "Precondition failed: Way  requires the nodes with id in (1307340578), which either do not exist, or are not visible." did not match with an expected pattern
- E: org.openstreetmap.josm.io.OsmApiException: ResponseCode=412, Error Header=<Precondition failed: Way  requires the nodes with id in (1307340578), which either do not exist, or are not visible.>

[Klumbumbus]

Closed as duplicate of #11386.
Should already be fixed.