feat: reject a set of invalid inputs for Color::from_hex

helix-view/src/graphics.rs

@@ -277,6 +277,9 @@ impl Color {
     /// assert_eq!(color1, color2);
     /// ```
     pub fn from_hex(hex: &str) -> Option<Self> {
+        if !(hex.starts_with('#') && hex.len() == 7) {
+            return None;
+        }
         match [1..=2, 3..=4, 5..=6].map(|i| hex.get(i).and_then(|c| u8::from_str_radix(c, 16).ok()))
         {
             [Some(r), Some(g), Some(b)] => Some(Self::Rgb(r, g, b)),