A valid method *) was converted into an equivalent piece of ClassFile API code **) for testing purposes.
*)
public static int run(int i) {
    try {
        if (i < 0) {
            throw new IllegalArgumentException();
        }
        throw new IndexOutOfBoundsException();
    } catch (IllegalArgumentException e) {
        return 0;
    } catch (Exception e) {
        return 1000;
    }
}
**)
mb.withCode(cb -> {
    cb.trying(
            tb -> {
                tb.block(bb -> {
                    bb.iload(0);
                    bb.branch(Opcode.IFGE, bb.endLabel()); // ifge L12
                    bb.new_(CD_IAE);
                    bb.dup();
                    bb.invokespecial(CD_IAE, "<init>", MTD_void);
                    bb.athrow();
                });
                tb.block(bb -> {
                    bb.new_(CD_IOBE);
                    bb.dup();
                    bb.invokespecial(CD_IOBE, "<init>", MTD_void);
                    bb.athrow();
                });
                // 20: {opcode: GOTO, target: 31} added by the ClassFile API
                // "31" exceeds the end of the Code attribute.
                // can be fixed by adding tb.return_();
            },
            catchBuilder -> {
                catchBuilder.catching(CD_IAE, bb -> {
                    bb.aload(1); // astore_1
                    bb.iconst_0(); // iconst_0
                    bb.ireturn(); // ireturn
                });
                catchBuilder.catching(CD_E, bb -> {
                    bb.aload(1); // astore_1
                    bb.sipush(1000); // sipush 1000
                    bb.ireturn(); // ireturn
                });
            }
    );
});
Then, building the classfile bytes throws the following exception:
java.lang.IllegalArgumentException: Detected branch target out of bytecode range at bytecode offset 20 of method run(int)
— max stack: 65535
— max locals: 65535
— attributes: []
// stack map frame @0: {locals: [int], stack: []}
0: {opcode: ILOAD_0, slot: 0}
1: {opcode: IFGE, target: 12}
4: {opcode: NEW, type: java/lang/IllegalArgumentException}
7: {opcode: DUP}
8: {opcode: INVOKESPECIAL, owner: java/lang/IllegalArgumentException, method name: <init>, method type: ()V}
11: {opcode: ATHROW}
12: {opcode: NEW, type: java/lang/IndexOutOfBoundsException}
15: {opcode: DUP}
16: {opcode: INVOKESPECIAL, owner: java/lang/IndexOutOfBoundsException, method name: <init>, method type: ()V}
19: {opcode: ATHROW}
20: {opcode: GOTO, target: 31}
23: {opcode: ALOAD_1, slot: 1}
24: {opcode: ICONST_0, constant value: 0}
25: {opcode: IRETURN}
26: {opcode: ALOAD_1, slot: 1}
27: {opcode: SIPUSH, constant value: 1000}
30: {opcode: IRETURN}

As can be seen, the instruction at offset 20: {opcode: GOTO, target: 31} was added to the output. This instruction jumps beyond the valid code range.

An example of the code is attached.