TestSwitchExpressionOp::unconditionalPattern lowers to a model with dead default branch missing a block argument in conditional branch from ^block_8 to ^block_10:

 ...
  ^block_8(%15 : java.type:"boolean"):
    cbranch %15 ^block_9 ^block_10;
  
  ^block_9:
    %16 : java.type:"java.lang.String" = constant @"default";
    branch ^block_10(%16);
  
  ^block_10(%17 : java.type:"java.lang.String"):
    return %17;