[JS IR BE] Fix inline classes workarounds

- Remove uninitialized return type check
- Remove unbound classifier symbol check

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/AutoboxingTransformer.kt

@@ -37,12 +37,7 @@ class AutoboxingTransformer(val context: JsIrBackendContext) : AbstractValueUsag
                 if (this.symbol.owner.let { it is IrSimpleFunction && it.isSuspend }) {
                     irBuiltIns.anyNType
                 } else {
-                    try {
-                        this.symbol.owner.returnType
-                    } catch (e: kotlin.UninitializedPropertyAccessException) {
-                        // TODO: Fix lateinit return types
-                        this.type
-                    }
+                    this.symbol.owner.returnType
                 }
             }
             is IrGetField -> this.symbol.owner.type

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MultipleCatchesLowering.kt

@@ -125,7 +125,7 @@ class MultipleCatchesLowering(val context: JsIrBackendContext) : FileLoweringPas
             private fun buildImplicitCast(value: IrExpression, toType: IrType, toTypeSymbol: IrClassifierSymbol) =
                 JsIrBuilder.buildTypeOperator(toType, IrTypeOperator.IMPLICIT_CAST, value, toType, toTypeSymbol)
 
-            private fun mergeTypes(types: List<IrType>) = types.commonSupertype().also {
+            private fun mergeTypes(types: List<IrType>) = types.commonSupertype(context.symbolTable).also {
                 assert(it.isSubtypeOf(context.irBuiltIns.throwableType) || it is IrDynamicType)
             }