fix: prevent Write(nil) from panicking

.github/workflows/test.yaml

@@ -10,7 +10,7 @@ on:
 
 jobs:
   lint:
-    uses: endobit/ci/.github/workflows/go-lint.yaml@main
+    uses: endobit/ci/.github/workflows/go-lint.yaml@v1.3.1
   test:
-    uses: endobit/ci/.github/workflows/go-test.yaml@main
+    uses: endobit/ci/.github/workflows/go-test.yaml@v1.3.1
     secrets: inherit

table.go

@@ -115,7 +115,8 @@ func New(opts ...func(*Table)) *Table {
 // flushed if a new struct type is written. If a is not a struct, an error table
 // will be added to the output.
 func (t *Table) Write(a any) {
-	if reflect.TypeOf(a).Kind() != reflect.Struct {
+	typ := reflect.TypeOf(a)
+	if typ == nil || typ.Kind() != reflect.Struct {
 		msg := struct {
 			Error error
 			Type  string

table_test.go

@@ -254,6 +254,21 @@ func TestWriteNonStruct(t *testing.T) {
 	}
 }
 
+func TestWriteNil(t *testing.T) {
+	var buf bytes.Buffer
+
+	tbl := New(WithWriter(&buf))
+
+	tbl.Write(nil)
+	_ = tbl.Flush()
+
+	output := buf.String()
+
+	if !strings.Contains(output, "not a struct") {
+		t.Errorf("expected error message in output, got: %q", output)
+	}
+}
+
 func TestEmptyTable(t *testing.T) {
 	var buf bytes.Buffer