test: add coverage for mem check on setOwnStr

object.go

@@ -548,7 +548,7 @@ func (o *baseObject) setOwnStr(name unistring.String, val Value, throw bool) boo
 			o.val.runtime.typeErrorResult(throw, "Cannot add property %s, object is not extensible", name)
 			return false
 		} else {
-			if o.val.runtime.shouldForceMemCheck {
+			if o.val != nil && o.val.runtime != nil && o.val.runtime.shouldForceMemCheck {
 				memCtx := newMemUsageContextClone()
 				if memCtx != nil {
 					memUsage, err := val.MemUsage(memCtx)

object_test.go

@@ -1,6 +1,7 @@
 package goja
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 	"strings"
@@ -829,3 +830,63 @@ func TestPrimitiveValueObjectMemUsage(t *testing.T) {
 		})
 	}
 }
+
+func TestSetOwnStr(t *testing.T) {
+	for _, tc := range []struct {
+		name                string
+		memLimit            uint64
+		expectedPanic       bool
+		shouldForceMemCheck bool
+	}{
+		{
+			name:                "should not panic when setting a value in an object",
+			memLimit:            1000,
+			expectedPanic:       false,
+			shouldForceMemCheck: false,
+		},
+		{
+			name:                "should panic when setting a value in an object over the mem limit and mem usage check is forced",
+			memLimit:            0,
+			expectedPanic:       true,
+			shouldForceMemCheck: true,
+		},
+		{
+			name:                "should not panic when setting a value in an object over the mem limit and mem usage check is not forced",
+			memLimit:            0,
+			expectedPanic:       false,
+			shouldForceMemCheck: false,
+		},
+		{
+			name:                "should not panic when setting a value in an object under the mem limit and mem usage check is forced",
+			memLimit:            1000,
+			expectedPanic:       false,
+			shouldForceMemCheck: true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			defer func() {
+				r := recover()
+				if tc.expectedPanic && r == nil {
+					t.Error("The code is expected to panic, but it didn't")
+				}
+				if !tc.expectedPanic && r != nil {
+					t.Errorf("The code panicked, but it should not have: %v", r)
+				}
+			}()
+			v := &Object{
+				runtime: NewWithContext(context.Background(), tc.shouldForceMemCheck),
+			}
+			o := &baseObject{
+				val:        v,
+				extensible: true,
+			}
+			o.init()
+			v.self = o
+
+			// Creating a mem usage context so it populates the package variable
+			NewMemUsageContext(100, tc.memLimit, 100, 100, 0.5, nil)
+
+			o.setOwnStr("test", valueInt(123), false)
+		})
+	}
+}