Change order of logic for dotnet-isolated that has worker config in functions (#7167)

* change order of logic for dotnet-isolated that has worker config in function defs

* Add comment to avoid future issues

Author: mhoeger

src/WebJobs.Script/Workers/Rpc/FunctionRegistration/RpcFunctionInvocationDispatcher.cs

@@ -171,21 +171,23 @@ public async Task InitializeAsync(IEnumerable<FunctionMetadata> functions, Cance
                 return;
             }
 
+            if (functions == null || functions.Count() == 0)
+            {
+                // do not initialize function dispatcher if there are no functions
+                return;
+            }
+
             var workerConfig = _workerConfigs.Where(c => c.Description.Language.Equals(_workerRuntime, StringComparison.OrdinalIgnoreCase)).FirstOrDefault();
             if (workerConfig == null)
             {
+                // Only throw if workerConfig is null AND some functions have been found.
+                // With .NET out-of-proc, worker config comes from functions.
                 throw new InvalidOperationException($"WorkerCofig for runtime: {_workerRuntime} not found");
             }
             _maxProcessCount = workerConfig.CountOptions.ProcessCount;
             _debounceMilliSeconds = (int)workerConfig.CountOptions.ProcessStartupInterval.TotalMilliseconds;
             ErrorEventsThreshold = 3 * _maxProcessCount;
 
-            if (functions == null || functions.Count() == 0)
-            {
-                // do not initialize function dispatcher if there are no functions
-                return;
-            }
-
             if (Utility.IsSupportedRuntime(_workerRuntime, _workerConfigs))
             {
                 State = FunctionInvocationDispatcherState.Initializing;