Fix crash in abstract property checking

src/compiler/checker.ts

@@ -34449,10 +34449,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             (flags & ModifierFlags.Abstract) && symbolHasNonMethodDeclaration(prop) &&
             (isThisProperty(location) || isThisInitializedObjectBindingExpression(location) || isObjectBindingPattern(location.parent) && isThisInitializedDeclaration(location.parent.parent))
         ) {
-            const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!);
-            if (declaringClassDeclaration && isNodeUsedDuringClassInitialization(location)) {
+            const parentSymbol = getParentOfSymbol(prop);
+            if (parentSymbol && parentSymbol.flags & SymbolFlags.Class && isNodeUsedDuringClassInitialization(location)) {
                 if (errorNode) {
-                    error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), getTextOfIdentifierOrLiteral(declaringClassDeclaration.name!));
+                    error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), symbolToString(parentSymbol));
                 }
                 return false;
             }

tests/baselines/reference/errorInUnnamedClassExpression.errors.txt

@@ -0,0 +1,21 @@
+errorInUnnamedClassExpression.ts(5,14): error TS2715: Abstract property 'bar' in class 'Foo' cannot be accessed in the constructor.
+errorInUnnamedClassExpression.ts(7,5): error TS1253: Abstract properties can only appear within an abstract class.
+errorInUnnamedClassExpression.ts(7,14): error TS7008: Member 'bar' implicitly has an 'any' type.
+
+
+==== errorInUnnamedClassExpression.ts (3 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/62920
+
+    let Foo = class {
+        constructor() {
+            this.bar++;
+                 ~~~
+!!! error TS2715: Abstract property 'bar' in class 'Foo' cannot be accessed in the constructor.
+        }
+        abstract bar;
+        ~~~~~~~~
+!!! error TS1253: Abstract properties can only appear within an abstract class.
+                 ~~~
+!!! error TS7008: Member 'bar' implicitly has an 'any' type.
+    };
+

tests/baselines/reference/errorInUnnamedClassExpression.symbols

@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/errorInUnnamedClassExpression.ts] ////
+
+=== errorInUnnamedClassExpression.ts ===
+// https://github.com/microsoft/TypeScript/issues/62920
+
+let Foo = class {
+>Foo : Symbol(Foo, Decl(errorInUnnamedClassExpression.ts, 2, 3))
+
+    constructor() {
+        this.bar++;
+>this.bar : Symbol(Foo.bar, Decl(errorInUnnamedClassExpression.ts, 5, 5))
+>this : Symbol(Foo, Decl(errorInUnnamedClassExpression.ts, 2, 9))
+>bar : Symbol(Foo.bar, Decl(errorInUnnamedClassExpression.ts, 5, 5))
+    }
+    abstract bar;
+>bar : Symbol(Foo.bar, Decl(errorInUnnamedClassExpression.ts, 5, 5))
+
+};
+

tests/baselines/reference/errorInUnnamedClassExpression.types

@@ -0,0 +1,28 @@
+//// [tests/cases/compiler/errorInUnnamedClassExpression.ts] ////
+
+=== errorInUnnamedClassExpression.ts ===
+// https://github.com/microsoft/TypeScript/issues/62920
+
+let Foo = class {
+>Foo : typeof Foo
+>    : ^^^^^^^^^^
+>class {    constructor() {        this.bar++;    }    abstract bar;} : typeof Foo
+>                                                                     : ^^^^^^^^^^
+
+    constructor() {
+        this.bar++;
+>this.bar++ : number
+>           : ^^^^^^
+>this.bar : any
+>         : ^^^
+>this : this
+>     : ^^^^
+>bar : any
+>    : ^^^
+    }
+    abstract bar;
+>bar : any
+>    : ^^^
+
+};
+

tests/cases/compiler/errorInUnnamedClassExpression.ts

@@ -0,0 +1,11 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/62920
+
+let Foo = class {
+    constructor() {
+        this.bar++;
+    }
+    abstract bar;
+};