diff --git a/Sources/Fuzzilli/Compiler/Compiler.swift b/Sources/Fuzzilli/Compiler/Compiler.swift
index 1a47ce67a..41d348fbc 100644
--- a/Sources/Fuzzilli/Compiler/Compiler.swift
+++ b/Sources/Fuzzilli/Compiler/Compiler.swift
@@ -988,45 +988,44 @@ public class JavaScriptCompiler {
             if unaryExpression.operator == "typeof" {
                 return emit(TypeOf(), withInputs: [argument]).output
             } else if unaryExpression.operator == "delete" {
-                let argumentExpression = unaryExpression.argument.expression!
-
-                if case .memberExpression(let memberExpression) = argumentExpression {
-                    let obj = try compileExpression(memberExpression.object)
-                    let isGuarded = memberExpression.isOptional
+                guard case .memberExpression(let memberExpression) = unaryExpression.argument.expression else {
+                    throw CompilerError.invalidNodeError("delete operator must be applied to a member expression")
+                }
 
-                    if memberExpression.name != "" {
-                        // Deleting a non-computed property (e.g., delete obj.prop)
-                        let propertyName = memberExpression.name
+                let obj = try compileExpression(memberExpression.object)
+                // isGuarded is true if the member expression is optional (e.g., obj?.prop)
+                let isGuarded = memberExpression.isOptional
+
+                if !memberExpression.name.isEmpty {
+                    // Deleting a non-computed property (e.g., delete obj.prop)
+                    let propertyName = memberExpression.name
+                    let instr = emit(
+                        DeleteProperty(propertyName: propertyName, isGuarded: isGuarded),
+                        withInputs: [obj]
+                    )
+                    return instr.output
+                } else {
+                    // Deleting a computed property (e.g., delete obj[expr])
+                    let propertyExpression = memberExpression.expression
+                    let propertyExpr = propertyExpression.expression
+                    let property = try compileExpression(propertyExpression)
+
+                    if case .numberLiteral(let numberLiteral) = propertyExpr {
+                        // Delete an element (e.g., delete arr[42])
+                        let index = Int64(numberLiteral.value)
                         let instr = emit(
-                            DeleteProperty(propertyName: propertyName, isGuarded: isGuarded),
+                            DeleteElement(index: index, isGuarded: isGuarded),
                             withInputs: [obj]
                         )
                         return instr.output
                     } else {
-                        // Deleting a computed property (e.g., delete obj[expr])
-                        let propertyExpression = memberExpression.expression
-                        let propertyExpr = propertyExpression.expression
-                        let property = try compileExpression(propertyExpression)
-
-                        if case .numberLiteral(let numberLiteral) = propertyExpr {
-                            // Delete an element (e.g., delete arr[42])
-                            let index = Int64(numberLiteral.value)
-                            let instr = emit(
-                                DeleteElement(index: index, isGuarded: isGuarded),
-                                withInputs: [obj]
-                            )
-                            return instr.output
-                        } else {
-                            // Use DeleteComputedProperty for other computed properties (e.g., delete obj["key"])
-                            let instr = emit(
-                                DeleteComputedProperty(isGuarded: isGuarded),
-                                withInputs: [obj, property]
-                            )
-                            return instr.output
-                        }
+                        // Use DeleteComputedProperty for other computed properties (e.g., delete obj["key"])
+                        let instr = emit(
+                            DeleteComputedProperty(isGuarded: isGuarded),
+                            withInputs: [obj, property]
+                        )
+                        return instr.output
                     }
-                } else {
-                    throw CompilerError.invalidNodeError("Invalid argument for delete operator; expected a member expression")
                 }
             } else {
                 guard let op = UnaryOperator(rawValue: unaryExpression.operator) else {