Codechange: Make INVALID_TE_ID a TextEffectID instead of a TextEffectMode.

Type-correctness?

src/texteff.hpp

@@ -20,12 +20,12 @@
 enum TextEffectMode {
 	TE_RISING, ///< Make the text effect slowly go upwards
 	TE_STATIC, ///< Keep the text effect static
-
-	INVALID_TE_ID = 0xFFFF,
 };
 
 typedef size_t TextEffectID;
 
+static const TextEffectID INVALID_TE_ID = UINT16_MAX;
+
 TextEffectID AddTextEffect(StringID msg, int x, int y, uint8_t duration, TextEffectMode mode);
 void InitTextEffects();
 void DrawTextEffects(DrawPixelInfo *dpi);