"unexpected combination" error

We just tested an import of https://github.com/eisop/checker-framework/commit/faf33e68377774fa276fad8e8717b8bfee48c42a and https://github.com/eisop/checker-framework/commit/ddae9715ce32cc0ae115baf039699fa1f13a8e9e, and we're seeing this crash:

import java.util.List;
import org.checkerframework.checker.nullness.qual.NonNull;

class A {
  List<A> attrs = or(x(), y());

  <T> @NonNull T or(T nullableValue, T defaultValue) {
    throw new UnsupportedOperationException();
  }

  List<A> x() {
    throw new UnsupportedOperationException();
  }

  <T> List<T> y() {
    throw new UnsupportedOperationException();
  }
}

error: StructuralEqualityComparer: unexpected combination:  type: [TYPEVAR class org.checkerframework.framework.type.AnnotatedTypeMirror$AnnotatedTypeVariable] capture#01 extends Object  supertype: [DECLARED class org.checkerframework.framework.type.AnnotatedTypeMirror$AnnotatedDeclaredType] A
    visitHistory = org.checkerframework.framework.type.StructuralEqualityVisitHistory@7b4b6dca
  ; The Checker Framework crashed.  Please report the crash.  Version: Checker Framework 3.42.0-eisop3-SNAPSHOT, branch master, 2024-02-04, commit 777b7dc. 
  Checker: class org.checkerframework.checker.nullness.KeyForSubchecker
  Visitor: class org.checkerframework.common.basetype.BaseTypeVisitor
  Compilation unit: A.java
  Last visited tree at line 5 column 3:
    List<A> attrs = or(x(), y());
  Exception: java.lang.Throwable; java.lang.Throwable
        at org.checkerframework.javacutil.BugInCF.<init>(BugInCF.java:22)
        at org.checkerframework.framework.type.visitor.AtmComboVisitor.defaultAction(AtmComboVisitor.java:66)
        at org.checkerframework.framework.type.StructuralEqualityComparer.defaultAction(StructuralEqualityComparer.java:58)
        at org.checkerframework.framework.type.StructuralEqualityComparer.defaultAction(StructuralEqualityComparer.java:31)
        at org.checkerframework.framework.type.visitor.AbstractAtmComboVisitor.visitTypevar_Declared(AbstractAtmComboVisitor.java:517)
        at org.checkerframework.framework.util.AtmCombo.accept(AtmCombo.java:638)
        at org.checkerframework.framework.type.StructuralEqualityComparer.areEqual(StructuralEqualityComparer.java:94)
        at org.checkerframework.framework.type.StructuralEqualityComparer.areEqualInHierarchy(StructuralEqualityComparer.java:104)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.areEqualInHierarchy(DefaultTypeHierarchy.java:343)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isContainedBy(DefaultTypeHierarchy.java:418)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isContainedMany(DefaultTypeHierarchy.java:664)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitTypeArgs(DefaultTypeHierarchy.java:641)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitDeclared_Declared(DefaultTypeHierarchy.java:560)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitDeclared_Declared(DefaultTypeHierarchy.java:50)
        at org.checkerframework.framework.util.AtmCombo.accept(AtmCombo.java:314)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isSubtype(DefaultTypeHierarchy.java:263)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isSubtype(DefaultTypeHierarchy.java:139)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:3316)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:3290)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:3211)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitVariable(BaseTypeVisitor.java:1660)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitVariable(BaseTypeVisitor.java:195)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:990)
        at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
        at org.checkerframework.framework.source.SourceVisitor.scan(SourceVisitor.java:95)
        at org.checkerframework.common.basetype.BaseTypeVisitor.scan(BaseTypeVisitor.java:442)
        at org.checkerframework.common.basetype.BaseTypeVisitor.scan(BaseTypeVisitor.java:195)
        at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
        at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
        at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
        at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
        at org.checkerframework.framework.source.SourceVisitor.visitClass(SourceVisitor.java:101)
        at org.checkerframework.common.basetype.BaseTypeVisitor.processClassTree(BaseTypeVisitor.java:646)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitClass(BaseTypeVisitor.java:601)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitClass(BaseTypeVisitor.java:195)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:808)
        at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:56)
        at org.checkerframework.framework.source.SourceVisitor.visit(SourceVisitor.java:89)
        at org.checkerframework.framework.source.SourceChecker.typeProcess(SourceChecker.java:1136)
        at org.checkerframework.common.basetype.BaseTypeChecker.typeProcess(BaseTypeChecker.java:556)
        at org.checkerframework.common.basetype.BaseTypeChecker.typeProcess(BaseTypeChecker.java:549)
        at org.checkerframework.javacutil.AbstractTypeProcessor$AttributionTaskListener.finished(AbstractTypeProcessor.java:193)
        at jdk.compiler/com.sun.tools.javac.api.ClientCodeWrapper$WrappedTaskListener.finished(ClientCodeWrapper.java:828)
        at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:132)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1415)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1372)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:972)
        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)

(with similar exception stack traces for the other visitors)

eisop / checker-framework

"unexpected combination" error #703