Fix a data race in the loadWAL function caused by reusing the same error var in multiple goroutines (#9259)
Fix a data race in the loadWAL function caused by reusing the same error var in multiple goroutines (#9259)

Signed-off-by: Callum Styan <106b387c595dcc1a235f6eff749ea0675b25b42d@gmail.com>
alileza/prometheus,prometheus/prometheus,prometheus/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,alileza/prometheus,alileza/prometheus,alileza/prometheus,keegancsmith/prometheus,alileza/prometheus,keegancsmith/prometheus,prometheus/prometheus