Unhelpful error when plugin installation fails: "Installation of PLUGIN_NAME failed"

[loop-evgeny]

Description of the Issue

I tried to install the "EditorConfig" plugin using PluginManager 1.4.12.0 and it displayed the following error dialog:

---

Installation Error

Installation of EditorConfig failed.

OK

This is completely unhelpful. The error should be more specific about what happened, e.g. HTTP error X from getting URL Y, error X trying to write file Y to directory Z, etc.

Steps to Reproduce the Issue

1. Open PluginManager.
2. Check EditorConfig in the list of plugins.
3. Click install.

Expected Behavior

No error or a helpful error.

Actual Behavior

The error above.

Debug Information

Notepad++ v7.5.9 (32-bit)
Build time : Oct 14 2018 - 15:02:52
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS : Windows 7 (64-bit)
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll NppExport.dll JSMinNPP.dll PluginManager.dll

[loop-evgeny]

Note: the underlying problem was resolved by enabling TLS 1.2, as noted in #114 (comment) This issue is about the bad error message which wastes way too much of the users' time.