Fixed compile error, ‘struct __MoDriv’ has no m ember named ‘errMsg’

site_ansto/motor_dmc2280.c

@@ -3038,7 +3038,7 @@ static void DMC2280Error(void *pData, int *iCode, char *error, int errLen){
     return;
   }
   strncpy(self->errorMsg, error, (size_t)errLen);
-  self->errMsg[errLen] = '\0';
+  self->errorMsg[errLen] = '\0';
 }
 
 /** \brief Attempts to recover from an error. Implements the TryAndFixIt