Better logging when converting unknown NSError to CHIP_ERROR. (#26011)

Otherwise we don't know what error we really had.

src/darwin/Framework/CHIP/MTRError.mm

@@ -238,6 +238,7 @@ + (CHIP_ERROR)errorToCHIPErrorCode:(NSError * _Nullable)error
     }
 
     if (error.domain != MTRErrorDomain) {
+        ChipLogError(Controller, "Trying to convert non-Matter error %@ to a Matter error code", error);
         return CHIP_ERROR_INTERNAL;
     }