Typos

Author: peachesontour

1-js/99-js-misc/01-proxy/01-error-nonexisting/task.md

@@ -1,8 +1,8 @@
-# Error on reading non-existant property
+# Error on reading non-existent property
 
-Usually, an attempt to read a non-existant property returns `undefined`.
+Usually, an attempt to read a non-existent property returns `undefined`.
 
-Create a proxy that throws an error for an attempt to read of a non-existant property instead.
+Create a proxy that throws an error for an attempt to read of a non-existent property instead.
 
 That can help to detect programming mistakes early.