Don't log error for auto-install attempt if Word isn't installed

[dstillman]

Timestamp: 4/17/17, 3:22:50 AM
Error: NS_ERROR_FAILURE: Word does not appear to be installed on this computer. Please install Microsoft Word, then try again. @[install:install.m:153]
Source File: file:///Users/dan/zotero-standalone-build/staging/Zotero.app/Contents/Resources/extensions/zoteroMacWordIntegration@zotero.org/components/zoteroMacWordIntegration.js
Line: 212

I don't think this used to happen. In any case, it would be better to avoid logging an error for a normal condition like this (but logging it for a manual install attempt from the prefs makes sense).

(Not sure if there are similar errors logged for WinWord and LibreOffice.)

[adomasven]

Been like this for at least 6 years.

This is just the general error logging mechanism and could be any error condition, including proper OS errors. In a manual install we prompt the user with these too. Might be a bit more work than warranted to add an additional way to return from obj-c library just to avoid such cases.