Added NULL check before unsubscribing from PasswordChanged (PasswordBindBehaviour)

[Mazzelfassel]

Description of Change

When working with the ConnectionStringBuilder I got a crash every time I closed the window. After some investigation I figured out, that the Problem is the PasswordBindBehaviour. When the window is closed the password-box is removed and the AssociatedObject property is set to null before the OnAssociatedObjectUnloaded method gets called. This results in an exception being thrown.

To prevent this I added a NULL check before the unsubscription is done. There should be no problems with memory leaks or lingering connectios even when not explicitly unsubscribing.

API Changes

None

Platforms Affected

• All

Behavioral Changes

None

Testing Procedure

PR Checklist

• I have included examples or tests
• I have updated the change log
• I am listed in the CONTRIBUTORS file
• Rebased on top of the target branch at time of PR
• Changes adhere to coding standard

[CLAassistant]

All committers have signed the CLA.

[ceo1647]

@Mazzelfassel, thanks for reporting and suggesting a fix. Will try to reproduce and check your fixes.