fix index out of range

Author: 4meepo

tagalign.go

@@ -221,15 +221,15 @@ func (w *Helper) Process(pass *analysis.Pass) { //nolint:gocognit
 			if err != nil {
 				// if tag value is not a valid string, report it directly
 				w.report(pass, field, column, errTagValueSyntax, field.Tag.Value)
-				fields = append(fields[:i], fields[i+1:]...)
+				fields = removeField(fields, i)
 				continue
 			}
 
 			tags, err := structtag.Parse(tag)
 			if err != nil {
 				// if tag value is not a valid struct tag, report it directly
 				w.report(pass, field, column, err.Error(), field.Tag.Value)
-				fields = append(fields[:i], fields[i+1:]...)
+				fields = removeField(fields, i)
 				continue
 			}
 
@@ -449,3 +449,11 @@ func max(a, b int) int {
 	}
 	return b
 }
+
+func removeField(fields []*ast.Field, index int) []*ast.Field {
+	if index < 0 || index >= len(fields) {
+		return fields
+	}
+
+	return append(fields[:index], fields[index+1:]...)
+}

testdata/bad_syntax_tag/example.go

@@ -10,8 +10,8 @@ type FooBar struct {
 type FooBar2 struct {
 	Foo int `json:"foo" validate:"required"`
 
-	Bar string `json:bar` // want `bad syntax for struct tag value`
-
-	FooFoo int8 `json:"foo_foo"`
-	BarBar int  `json:"bar_bar" validate:"required"`
+	FooFoo int8   `json:"foo_foo"`
+	BarBar int    `json:"bar_bar" validate:"required"`
+	XXX    int    `json:"xxx"     validate:"required"`
+	Bar    string `json:bar` // want `bad syntax for struct tag value`
 }