Consider code like:
---
class Test {

    public void testMethod(Object o) {
        String r;

        switch (o) {
            case String s && s.length() > 0 && s.charAt(0) != ' ' -> r = s;
            default -> r = null;
        }
    }

}
---

This crashes javac:
---
$ javac --enable-preview -source 17 Test.java
Note: Test.java uses preview features of Java SE 17.
Note: Recompile with -Xlint:preview for details.
An exception has occurred in the compiler (17-internal). 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, the following diagnostic, and the parameters passed to the Java compiler 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.util.Bits.isMember(Bits.java:231)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.checkInit(Flow.java:1896)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.checkInit(Flow.java:1890)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitIdent(Flow.java:2776)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCIdent.accept(JCTree.java:2584)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.scan(Flow.java:1682)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.scanExpr(Flow.java:1939)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitAssign(Flow.java:2705)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:2041)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.scan(Flow.java:1682)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitExec(TreeScanner.java:219)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1584)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.scan(Flow.java:1682)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.handleSwitch(Flow.java:2409)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitSwitch(Flow.java:2374)
[snip]
---