Merge pull request #981 from pkuehnel/fix/interpretPvNullValuesAs0

Fix/interpret pv null values as0

TeslaSolarCharger/Server/Services/PvValueService.cs

@@ -394,10 +394,11 @@ internal double GetValueFromResult(string? pattern, string result, NodePatternTy
     {
         switch (patternType)
         {
+            //allow JSON values to be null, as this is needed by SMA inverters: https://tff-forum.de/t/teslasolarcharger-laden-nach-pv-ueberschuss-mit-beliebiger-wallbox/170369/2728?u=mane123
             case NodePatternType.Json:
                 _logger.LogTrace("Extract overage value from json {result} with {pattern}", result, pattern);
                 result = (JObject.Parse(result).SelectToken(pattern ?? throw new ArgumentNullException(nameof(pattern))) ??
-                          throw new InvalidOperationException("Could not find token by pattern")).Value<string>() ?? throw new InvalidOperationException("Extracted Json Value is null");
+                          throw new InvalidOperationException("Could not find token by pattern")).Value<string>() ?? "0";
                 break;
             case NodePatternType.Xml:
                 _logger.LogTrace("Extract overage value from xml {result} with {pattern}", result, pattern);