Cannot invoke "org.dynmap.markers.Marker.deleteMarker()" because "oldm" is null

[melvinlemoine]

[WARN] [dynmap-mobs] Task #7328938 for dynmap-mobs v1.3 generated an exception java.lang.NullPointerException: Cannot invoke "org.dynmap.markers.Marker.deleteMarker()" because "oldm" is null at org.dynmap.mobs.DynmapMobsPlugin$VehicleUpdate.run(DynmapMobsPlugin.java:469) ~[?:?] at org.bukkit.craftbukkit.v1_17_R1.scheduler.CraftTask.run(CraftTask.java:100) ~[patched_1.17.1.jar:git-Paper-107] at org.bukkit.craftbukkit.v1_17_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:468) ~[patched_1.17.1.jar:git-Paper-107] at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1490) ~[patched_1.17.1.jar:git-Paper-107] at net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:479) ~[patched_1.17.1.jar:git-Paper-107] at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1406) ~[patched_1.17.1.jar:git-Paper-107] at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1188) ~[patched_1.17.1.jar:git-Paper-107] at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:316) ~[patched_1.17.1.jar:git-Paper-107] at java.lang.Thread.run(Thread.java:831) [?:?]