Fixed Handled error in OAuth2ExtraTokenMiddleware when authheader has `Bearer` with no token-string following up #1574

Job	Run time
Test Demo Relying Party (18.x)	15s
Test Demo Relying Party (20.x)	12s
Test Package (Python 3.10, Django 4.2)	2m 24s
Test Package (Python 3.10, Django 5.0)	2m 46s
Test Package (Python 3.10, Django 5.1)	3m 15s
Test Package (Python 3.10, Django main)	3m 49s
Test Package (Python 3.11, Django 4.2)	2m 21s
Test Package (Python 3.11, Django 5.0)	2m 46s
Test Package (Python 3.11, Django 5.1)	3m 15s
Test Package (Python 3.11, Django main)	3m 41s
Test Package (Python 3.12, Django 4.2)	2m 25s
Test Package (Python 3.12, Django 5.0)	2m 51s
Test Package (Python 3.12, Django 5.1)	3m 19s
Test Package (Python 3.12, Django main)	3m 47s
Test Package (Python 3.8, Django 4.2)	2m 25s
Test Package (Python 3.9, Django 4.2)	2m 33s
Test successful	1s
	42m 5s

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