Updated get file extension logic

src/files/get_file_extension.test.ts

@@ -33,10 +33,19 @@ Deno.test(
         });
         await test.step({
             name: 'Path without file extension.',
+            fn: () => {
+                assertEquals(
+                    getFileExtension('path/without/file'),
+                    null
+                );
+            }
+        });
+        await test.step({
+            name: 'Path without file extension, but trailing slash (/).',
             fn: () => {
                 assertEquals(
                     getFileExtension('path/without/file/'),
-                    undefined
+                    null
                 );
             }
         });

src/files/get_file_extension.ts

@@ -2,8 +2,15 @@
  * This function takes in a path to a file and returns the file extension (without the `.`).
  * 
  * @param path The path to the file
- * @returns The file extension or undefined if no file extension was found
+ * @returns The file extension or null if no file extension was found
  */
-export function getFileExtension(path : string) : string | undefined {
-    return path.replace(/.+\.([^/.]+$)/, (_, extension) => extension);
+export function getFileExtension(path : string) : string | null {
+    const matchFileExtension = /\.([^/.]+$)/;
+    const fileExtension = path.match(matchFileExtension)
+
+    if (fileExtension === null) {
+        return null
+    }
+
+    return fileExtension[1]
 }