diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/resolve/TreeResolveUtils.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/resolve/TreeResolveUtils.kt
index d6fdbd030c3..9736900357a 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/resolve/TreeResolveUtils.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/resolve/TreeResolveUtils.kt
@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirClassifierSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeAliasSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.fir.types.ConeAttributes
-import org.jetbrains.kotlin.fir.types.ConeClassErrorType
 import org.jetbrains.kotlin.fir.types.ConeLookupTagBasedType
 import org.jetbrains.kotlin.fir.types.ConeTypeProjection
 import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
@@ -36,6 +35,5 @@ fun FirClassifierSymbol<*>.constructType(
                 attributes = attributes
             )
         }
-        else -> error("!")
     }
 }
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirClassifierSymbol.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirClassifierSymbol.kt
index b1a2a8defe4..26f2c31d40d 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirClassifierSymbol.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirClassifierSymbol.kt
@@ -10,7 +10,7 @@ import org.jetbrains.kotlin.fir.declarations.FirDeclaration
 import org.jetbrains.kotlin.fir.symbols.AbstractFirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.ConeClassifierLookupTag
 
-abstract class FirClassifierSymbol<E> : AbstractFirBasedSymbol<E>()
+sealed class FirClassifierSymbol<E> : AbstractFirBasedSymbol<E>()
         where E : FirSymbolOwner<E>, E : FirDeclaration {
     abstract fun toLookupTag(): ConeClassifierLookupTag
 }