Fix & regression test for use-after-free introduced in bb117ff

tldr, avoid freeing memory before passing it along to another function.

Author: phillmv

src/inlines.c

@@ -1178,6 +1178,7 @@ static cmark_node *handle_close_bracket(cmark_parser *parser, subject *subj) {
       // being replacing the opening '[' text node with a `^footnote-ref]` node.
       cmark_node_insert_before(opener->inl_text, fnref);
 
+      process_emphasis(parser, subj, opener->previous_delimiter);
       // sometimes, the footnote reference text gets parsed into multiple nodes
       // i.e. '[^example]' parsed into '[', '^exam', 'ple]'.
       // this happens for ex with the autolink extension. when the autolinker
@@ -1191,8 +1192,6 @@ static cmark_node *handle_close_bracket(cmark_parser *parser, subject *subj) {
       // the opener->inl_text->next.
       //
       // therefore, here we walk thru the list and free them all up
-      process_emphasis(parser, subj, opener->previous_delimiter);
-
       cmark_node *next_node;
       cmark_node *current_node = opener->inl_text->next;
       while(current_node) {

test/regression.txt

@@ -338,3 +338,19 @@ It has another footnote that contains many different characters (the autolinker
 </ol>
 </section>
 ````````````````````````````````
+
+Footnotes interacting with strikethrough should not lead to a use-after-free
+
+```````````````````````````````` example footnotes autolink strikethrough table
+|Tot.....[^_a_]|
+.
+<p>|Tot.....[^_a_]|</p>
+````````````````````````````````
+
+Footnotes interacting with strikethrough should not lead to a use-after-free pt2
+
+```````````````````````````````` example footnotes autolink strikethrough table
+[^~~is~~1]
+.
+<p>[^~~is~~1]</p>
+````````````````````````````````