codec: webvtt: handle invalid values as specific type

refs #29533

This reverts commit 7f16b5681f.

modules/codec/webvtt/CSSGrammar.y

@@ -776,7 +776,7 @@ term:
   | UNICODERANGE maybe_space { $$.type = TYPE_UNICODERANGE; $$.psz = $1; }
   | IDSEL maybe_space { $$.type = TYPE_HEXCOLOR; $$.psz = $1; }
   | HASH maybe_space { $$.type = TYPE_HEXCOLOR; $$.psz = $1; }
-  | '#' maybe_space { $$.type = TYPE_HEXCOLOR; $$.psz = NULL; } /* Handle error case: "color: #;" */
+  | '#' maybe_space { $$.type = TYPE_INVALID; } /* Handle error case: "color: #;" */
   /* FIXME: according to the specs a function can have a unary_operator in front. I know no case where this makes sense */
   | function {
       $$ = $1;

modules/codec/webvtt/css_parser.h

@@ -37,6 +37,7 @@ typedef struct
     vlc_css_expr_t *function;
     enum
     {
+        TYPE_INVALID,
         TYPE_NONE = 0,
         TYPE_EMS,
         TYPE_EXS,

modules/codec/webvtt/css_style.c

@@ -175,8 +175,6 @@ void webvtt_FillStyleFromCssDeclaration( const vlc_css_declaration_t *p_decl, te
                 term = &p_decl->expr->seq[i].term;
                 if( term->type < TYPE_STRING )
                     continue;
-                if( term->type == TYPE_HEXCOLOR && term->psz == NULL) // Handle error case: "color: #;"
-                    continue;
                 i_total += strlen( term->psz );
                 if( term->type == TYPE_STRING )
                     i_total += 2;
@@ -190,8 +188,6 @@ void webvtt_FillStyleFromCssDeclaration( const vlc_css_declaration_t *p_decl, te
                     term = &p_decl->expr->seq[i].term;
                     if( term->type < TYPE_STRING )
                         continue;
-                    if( term->type == TYPE_HEXCOLOR && term->psz == NULL) // Handle error case: "color: #;"
-                        continue;
                     if( i > 0 )
                         strcat( psz, ", " );
                     i_total += strlen( term->psz );