[2.2.0] Wingpanel crashes upon attempting to summon calendar widget

## Prerequisites
- [x] I have searched open and closed issues for duplicates.

## Describe the bug
Clicking on datetime indicator to summon calendar widget will always crash wingpanel as seen here:


### To Reproduce
Steps to reproduce the behavior:
1. Click on date/time to bring up calendar widget.
2. Wingpanel will crash.

### Expected behavior
For the wingpanel calendar widget to appear.

### Logs
[Can be found here.](https://pastebin.com/p4yPTzhL)

For brevity's sake, this seems to be the issue:
`Nov 03 07:55:49 danny kernel: wingpanel[8788]: segfault at 20 ip 00007f02a67ae6d4 sp 00007ffcbcf8a3a8 error 4 in libdatetime.so[7f02a6799000+21000]`

## Platform Information

OS:
elementary OS Juno
Running Linux 5.0.0-32-generic and GTK Version 3.22.30

Hardware:
Lenovo Ideapad 320
Dual-Core AMD A12-9720P RADEON R7, 12 COMPUTE CORES 4C+8G
Advanced Micro Devices, Inc. [AMD/ATI] Wani [Radeon R5/R6/R7 Graphics] (rev c8)

Please check what applies:
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- [x] I'm using the latest released stable version

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