Reduce logging severity in TextView tests

CHANGELOG

@@ -1,6 +1,7 @@
 v1.4.7 (WIP)
 - Add Box.SetBackgroundTransparent
 - Add List.SetSelectedAlwaysCentered
+- Fix default background transparency of Flex and Grid
 
 v1.4.6 (2020-05-18)
 - Add Box.ShowFocus

textview_test.go

@@ -201,13 +201,16 @@ func TestTextViewMaxLines(t *testing.T) {
 
 	// append 100 lines with no limit set:
 	for i := 0; i < 100; i++ {
-		tv.Write([]byte(fmt.Sprintf("L%d\n", i)))
+		_, err := tv.Write([]byte(fmt.Sprintf("L%d\n", i)))
+		if err != nil {
+			t.Errorf("failed to write to TextView: %s", err)
+		}
 	}
 
 	// retrieve the total text and see we have the 100 lines:
 	count := strings.Count(tv.GetText(true), "\n")
 	if count != 100 {
-		t.Fatalf("Expected 100 lines, got %d", count)
+		t.Errorf("expected 100 lines, got %d", count)
 	}
 
 	// now set the maximum lines to 20, this should clip the buffer:
@@ -215,12 +218,15 @@ func TestTextViewMaxLines(t *testing.T) {
 	// verify buffer was clipped:
 	count = len(strings.Split(tv.GetText(true), "\n"))
 	if count != 20 {
-		t.Fatalf("Expected 20 lines, got %d", count)
+		t.Errorf("expected 20 lines, got %d", count)
 	}
 
 	// append 100 more lines:
 	for i := 100; i < 200; i++ {
-		tv.Write([]byte(fmt.Sprintf("L%d\n", i)))
+		_, err := tv.Write([]byte(fmt.Sprintf("L%d\n", i)))
+		if err != nil {
+			t.Errorf("failed to write to TextView: %s", err)
+		}
 	}
 
 	// Sice max lines is set to 20, we should still get 20 lines:
@@ -228,12 +234,12 @@ func TestTextViewMaxLines(t *testing.T) {
 	lines := strings.Split(txt, "\n")
 	count = len(lines)
 	if count != 20 {
-		t.Fatalf("Expected 20 lines, got %d", count)
+		t.Errorf("expected 20 lines, got %d", count)
 	}
 
 	// and those 20 lines should be the last ones:
 	if lines[0] != "L181" {
-		t.Fatalf("Expected to get L181, got %s", lines[0])
+		t.Errorf("expected to get L181, got %s", lines[0])
 	}
 
 }