fix(Auth): Add underlying error details to session error (#3364) #18

Job	Run time
Build Amplify Swift for macOS / Build Amplify-Package \| macOS	7m 57s
Build Amplify Swift for iOS / Build Amplify-Package \| iOS	11m 41s
Build Amplify Swift for tvOS / Build Amplify-Package \| tvOS	14m 3s
Build Amplify Swift for watchOS / Build Amplify-Package \| watchOS	11m 47s
Confirm Passing Build Steps	1s
	45m 29s

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