NPE in MediatedFileChannel in IOException due to insufficient permission

[Peter Beaman]

Ran across this while debugging something else:

Thread [main] (Suspended (exception NullPointerException))
 MediatedFileChannel.tryLock(long, long, boolean) line: 224
 VolumeStorageV2.lockChannel() line: 549
 VolumeStorageV2.open() line: 192
 Volume.open(Persistit) line: 437
 Persistit.initializeVolumes() line: 672
 Persistit.initialize(Configuration) line: 595
 Persistit.initialize(Properties) line: 559
 CLI.open(String, String, String, int, boolean) line: 735
 NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]
 NativeMethodAccessorImpl.invoke(Object, Object[]) line: 57
 DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43
 Method.invoke(Object, Object...) line: 616
 CLI$Command.execute(CLI, ArgParser) line: 484
 CLI$Command.access$600(CLI$Command, CLI, ArgParser) line: 470
 CLI.commandLoop() line: 643
 CLI.access$1200(CLI) line: 144
 CLI$12.runTask() line: 1328
 Persistit.main(String[]) line: 2507

due to inability to open the lock channel file. Pretty minor, but needs to get fixed sometime.

[Peter Beaman (pbeaman)]

To explain: this is an attempt to open a database using the CLI in a user account that does not have permission to access the files. The error should be reported clearly. Instead, an unhelpful NPE is generated.