Description:
An abbreviation that should end with a period in the custom dictionary doesn't even when a period is in a mid position, and editing it to add the ending period crashes LO.

Steps to Reproduce:
1. In Writer, have a document with text open.

2. Press F7, for Spelling. (I did it with English (USA).)

3. Click the Options... button.

4. For the user-defined dictionaries, leave as preselected Standard [All] and click the Edit... button.

5. In my case, the first entry and the editable-field entry were "a.m", without quotation marks or a trailing period. Add a trailing period.

Actual Results:
This immediately crashes LibreOffice, specifically libreoffice-core, versions 1:6.3.3.2-7.fc31.x86_64 and 1:6.3.4.2-2.fc31.x86_64. On restarting LO, recovering the formerly-open document is the first step. On repeating the STR, the "a.m" will not have been edited.

Expected Results:
Adding of the trailing period or ignoring of the attempt to add it; and able to continue work on the document without a crash.


Reproducible: Always


User Profile Reset: Yes



Additional Info:
Apparently, entries can have periods in the middle but not trailing.

I don't have an OpenGL setting.

The problem persists in version 6.3.4.2.0+ (build ID 6.3.4.2-2.fc31). I'm not prepared to install a newer or unstable verion.

Possibly relevant: Bug 128383, bug 128475, and bug 128823.