Adds hash table write error alert.

[znruss]

Writing can silently fail on certain systems (like mine). I don't know how to prevent it, but here's a few lines to add in error alerts.

[ged-jenkins]

Can one of the admins verify this patch?

[ctb]

jenkins, please test this.

[mr-c]

test this please

[mr-c]

Can one of the admins verify this patch?

[mr-c]

ok to test

[mr-c]

handing back to @ctb to consider

• Is it mergable
• Did it pass the tests?
  N/A If it introduces new functionality in scripts/ is it tested?
  Check for code coverage.
• Is it well formatted? Look at pep8/pylint, cppcheck, and
  make doc output. Use autopep8 and astyle -A10 if needed.
• Is it documented in the Changelog?

[mr-c]

@znruss Does #333 address your needs?

[ctb]

After looking at this, it seems like an OK addition to add write error human-readable output. It's obviously not the long-term fix, though (see #443 for that). @mr-c, what do you think?

[mr-c]

Sure, this is fine for now. I'll check it over and merge it in.