[FIR] Add expression field to FirErrorExpression

It is used to report diagnostics even in erroneous code (within ILLEGAL_SELECTOR for instance).

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/BuilderConfigurator.kt

@@ -152,6 +152,10 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
             defaultNull("label")
         }
 
+        builder(errorExpression) {
+            defaultNull("expression")
+        }
+
         builder(errorLoop) {
             defaultNull("label")
         }

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/ImplementationConfigurator.kt

@@ -133,7 +133,7 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
 
         impl(errorLoop) {
             default("block", "FirEmptyExpressionBlock()")
-            default("condition", "FirErrorExpressionImpl(source, mutableListOf(), ConeStubDiagnostic(diagnostic))")
+            default("condition", "FirErrorExpressionImpl(source, mutableListOf(), ConeStubDiagnostic(diagnostic), null)")
             useTypes(emptyExpressionBlock, coneStubDiagnosticType)
         }
 

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -99,6 +99,10 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +body(nullable = true, withReplace = true).withTransform()
         }
 
+        errorExpression.configure {
+            +field("expression", expression, nullable = true)
+        }
+
         errorFunction.configure {
             +symbol("FirErrorFunctionSymbol")
             +typeParameters