Fix null handling in OuraRingConfigurationConverter

Author: mpgxvii

oura-library/src/main/kotlin/org/radarbase/oura/converter/OuraRingConfigurationConverter.kt

@@ -46,11 +46,11 @@ class OuraRingConfigurationConverter(
             time = System.currentTimeMillis() / 1000.0
             timeReceived = System.currentTimeMillis() / 1000.0
             id = data.get("id")?.textValue()
-            color = data.get("color")?.textValue()?.classifyColor()
-            design = data.get("design")?.textValue()?.classifyDesign()
+            color = data.get("color")?.textValue()?.classifyColor() ?: OuraRingColor.UNKNOWN
+            design = data.get("design")?.textValue()?.classifyDesign() ?: OuraRingDesign.UNKNOWN
             firmwareVersion = data.get("firmware_version")?.textValue()
-            hardwareType = data.get("hardware_type")?.textValue()?.classifyHardware()
-            setUpAt = setupTime?.toEpochMilli()?.let { it / 1000.0 }
+            hardwareType = data.get("hardware_type")?.textValue()?.classifyHardware() ?: OuraRingHardwareType.UNKNOWN
+            setUpAt = setupTime?.toEpochMilli()?.let { it / 1000.0 } 
             size = data.get("size")?.intValue()
         }.build()
     }