Warn about incorrect icon name and handle gracefully (#1241)

* warn about incorrect icon name and handle gracefully

* add changeset

Author: braden-godley

.changeset/tough-balloons-breathe.md

@@ -0,0 +1,5 @@
+---
+'feather-icons': patch
+---
+
+Feather no longer breaks when trying to replace an icon using an invalid name

src/replace.js

@@ -31,6 +31,11 @@ function replaceElement(element, attrs = {}) {
   const name = elementAttrs['data-feather'];
   delete elementAttrs['data-feather'];
 
+  if (icons[name] === undefined) {
+    console.warn(`feather: '${name}' is not a valid icon`);
+    return;
+  }
+
   const svgString = icons[name].toSvg({
     ...attrs,
     ...elementAttrs,