Skip and display warning if tag does not match (#59)

Co-authored-by: CrazyMax <crazy-max@users.noreply.github.com>

dist/index.js

@@ -518,10 +518,16 @@ class Meta {
         else {
             tmatch = vraw.match(tag.attrs['pattern']);
         }
-        if (tmatch) {
-            vraw = tmatch[tag.attrs['group']];
-            latest = true;
+        if (!tmatch) {
+            core.warning(`${tag.attrs['pattern']} does not match ${vraw}.`);
+            return version;
         }
+        if (typeof tmatch[tag.attrs['group']] === 'undefined') {
+            core.warning(`Group ${tag.attrs['group']} does not exist for ${tag.attrs['pattern']} pattern.`);
+            return version;
+        }
+        vraw = tmatch[tag.attrs['group']];
+        latest = true;
         if (version.main == undefined) {
             version.main = vraw;
         }