Fixed panic when Highlight is called before the first call to Draw.

textview.go

@@ -1,6 +1,7 @@
 package tview
 
 import (
+	"math"
 	"strings"
 	"sync"
 
@@ -841,17 +842,24 @@ func (t *TextView) resetIndex() {
 // parseAhead parses the text buffer starting at the last line in
 // [TextView.lineIndex] until either the end of the buffer or until stop returns
 // true for the last complete line that was parsed. If wrapping is enabled,
-// width will be used as the available screen width.
+// width will be used as the available screen width. If width is 0, it is
+// assumed that there is no wrapping. This can happen when this function is
+// called before the first time [TextView.Draw] is called.
 //
 // There is no guarantee that stop will ever be called.
 //
 // The function adds entries to the [TextView.lineIndex] slice and the
 // [TextView.regions] map and adjusts [TextView.longestLine].
 func (t *TextView) parseAhead(width int, stop func(lineNumber int, line *textViewLine) bool) {
-	if t.text.Len() == 0 || width == 0 {
+	if t.text.Len() == 0 {
 		return // No text. Nothing to parse.
 	}
 
+	// If width is 0, make it infinite.
+	if width == 0 {
+		width = math.MaxInt
+	}
+
 	// What kind of tags do we scan for?
 	var options stepOptions
 	if t.styleTags {