ADDITIONAL SYSTEM INFORMATION :
uname -a
Linux tinkywinky 3.10.0-862.11.6.el7.x86_64 #1 SMP Fri Aug 10 16:55:11 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

 javac --version
Picked up JAVA_TOOL_OPTIONS: --enable-preview
javac 12

A DESCRIPTION OF THE PROBLEM :
The following code fails to compile:
package com.rockwellcollins.ana.gui;

public class A
{
   static String a;
   static String b;
   
   static
   {
      A.a = "not me";

      A.b =
         A.a == null
            ? null
            : switch( "not me" )
              {
                 default -> null;
              };
   }
}



STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
 javac --enable-preview --release 12 -d classes A.java

where A.java contains:
public class A
{
   static String a;
   static String b;
   
   static
   {
      A.a = "not me";

      A.b =
         A.a == null
            ? null
            : switch( "not me" )
              {
                 default -> null;
              };
   }
}




EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Successful compilation
ACTUAL -
Picked up JAVA_TOOL_OPTIONS: --enable-preview
Note: A.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.visitVarDef(Gen.java:1053)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:962)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:595)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:630)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:616)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:667)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitLetExpr(Gen.java:2300)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$LetExpr.accept(JCTree.java:3026)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:853)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitConditional(Gen.java:1835)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCConditional.accept(JCTree.java:1452)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:853)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitAssign(Gen.java:1951)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:1953)
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.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)

---------- BEGIN SOURCE ----------
public class A
{
   static String a;
   static String b;
   
   static
   {
      A.a = "not me";

      A.b =
         A.a == null
            ? null
            : switch( "not me" )
              {
                 default -> null;
              };
   }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Code without switch expression in ternary operator.

FREQUENCY : always