[21][Enhanced Switch] Bogus error: "Cannot mix pattern with other case labels"

[srikanth-sankaran]

Test case: (project should be built at source level 21) (22+ works ok)

public class X {	
	static void foo(Object o) {
	    switch (o) {
	        case Character c, Integer i:                 // Compile-time error
	            break;
	        default:
	        	break;
	    }
	}
} 

We report 3 errors on line 4:

	- Named pattern variables are not allowed here
	- Named pattern variables are not allowed here
	- Cannot mix pattern with other case labels

The last one i.e Cannot mix pattern with other case labels is wrong.