Code:

// SwTest.java
public class SwTest {
    public static void main(String[] args) {
        System.out.println(switch (0) {
           default -> {
               try {
                   break 1;
               }
               catch (Exception ex) {
                   break 2;
               }
               finally {
                   break 3;
               }
           }
        });
    }
}

Steps to reproduce:
> "C:\Program Files\Java\jdk-12\bin\java.exe" --version
openjdk 12 2019-03-19
OpenJDK Runtime Environment (build 12+33)
OpenJDK 64-Bit Server VM (build 12+33, mixed mode, sharing)
> "C:\Program Files\Java\jdk-12\bin\javac.exe" --release 12 --enable-preview SwTest.java

Expected: successful compilation

Actual result: compiler crash

Note: SwTest.java uses preview language features.
Note: Recompile with -Xlint:preview for details.
An exception has occurred in the compiler (12). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.AssertionError
at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBreak(Gen.java:1707)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBreak.accept(JCTree.java:1561)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1067)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen$3.genLast(Gen.java:1450)
at jdk.compiler/com.sun.tools.javac.jvm.Gen$3.gen(Gen.java:1446)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genFinalizer(Gen.java:341)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.unwind(Gen.java:353)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.unwindBreak(Gen.java:1747)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBreak(Gen.java:1735)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBreak.accept(JCTree.java:1561)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1067)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genTry(Gen.java:1479)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitTry(Gen.java:1467)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCTry.accept(JCTree.java:1381)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1067)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:651)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.handleSwitch(Gen.java:1337)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.doHandleSwitchExpression(Gen.java:1205)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitSwitchExpression(Gen.java:1172)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCSwitchExpression.accept(JCTree.java:1315)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:853)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genArgs(Gen.java:872)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitApply(Gen.java:1808)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1709)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:853)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitExec(Gen.java:1702)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1519)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1067)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:937)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:900)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:872)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2345)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:756)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1635)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1603)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:311)
at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:170)
at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)