Remove returning of fault when cgmSource is nil in readCGMResult(), only log message

FreeAPS/Sources/APS/CGM/CGMType.swift

@@ -108,5 +108,4 @@ enum CGMType: String, JSON, CaseIterable, Identifiable {
 enum GlucoseDataError: Error {
     case noData
     case unreliableData
-    case noGlucoseSource
 }

FreeAPS/Sources/APS/CGM/PluginSource.swift

@@ -177,7 +177,6 @@ extension PluginSource: CGMManagerDelegate {
                 .deviceManager,
                 "No glucose source available."
             )
-            return .failure(GlucoseDataError.noGlucoseSource)
         }
 
         switch readingResult {