The problem seems to rest with Safari not being able to open it's default "start page" -- which isn't an actual page but generated based on past history in Safari.
Like AncientCoder said -- inserting a link in Notes (you can insert one, try https://www.apple.com/ ) you should right click the link and "Open In..." and then select Safari. This should cause the browser to open (and not crash... wow imagine that!).
Now this is the crucial part! Open the preferences, on the General tab -- change the homepage to a known good website (like apple, see link above). Then change "New tabs open with:" to Homepage, as well as "New windows open with:" and "Safari opens with:" all to "Homepage". Close the Preferences and Safari should work like normal.
Cruxmono
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