Fixed Handled error in OAuth2ExtraTokenMiddleware when authheader has `Bearer` with no token-string following up #1608

Job	Run time
Test Demo Relying Party (18.x)	14s
Test Demo Relying Party (20.x)	14s
Test Package (Python 3.10, Django 4.2)	2m 32s
Test Package (Python 3.10, Django 5.0)	2m 56s
Test Package (Python 3.10, Django 5.1)	3m 27s
Test Package (Python 3.10, Django main)	4m 6s
Test Package (Python 3.11, Django 4.2)	2m 29s
Test Package (Python 3.11, Django 5.0)	2m 59s
Test Package (Python 3.11, Django 5.1)	3m 20s
Test Package (Python 3.11, Django main)	4m 0s
Test Package (Python 3.12, Django 4.2)	2m 36s
Test Package (Python 3.12, Django 5.0)	3m 8s
Test Package (Python 3.12, Django 5.1)	3m 28s
Test Package (Python 3.12, Django main)	4m 9s
Test Package (Python 3.8, Django 4.2)	2m 33s
Test Package (Python 3.9, Django 4.2)	2m 32s
Test successful	1s
	44m 44s

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