I am not sure what is causing the error. If all the inputs coming to your 'Input Switch' block are of the same type, then you should not see this error. To ensure that entities are of the same type, you have to give them the same 'Entity type name' to all of them and they all should have the same attributes.
Please see the attached model, where I have the 'Entity Find' block that outputs the extracted entities to an 'Input Switch'. Both the extracted entities and the other stream of entities going to the Input Switch are of type 'Entity'. You can see the output type of the blocks by going to the menu bar and turning on 'Display' -> 'Signals & Ports' -> 'Port Data Types'.