Fixing readonly ops not to modify context when paths dont exist

pkg/yqlib/operator_comments_test.go

@@ -62,6 +62,22 @@ var commentOperatorScenarios = []expressionScenario{
 			"D0, P[], (doc)::a: cat\n\n# cat\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   `a: cat`,
+		expression: `. footComment=.b.d`,
+		expected: []string{
+			"D0, P[], (doc)::a: cat\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `a: cat`,
+		expression: `. footComment|=.b.d`,
+		expected: []string{
+			"D0, P[], (doc)::a: cat\n",
+		},
+	},
 	{
 		description: "Remove comment",
 		document:    "a: cat # comment\nb: dog # leave this",