Added null_check_test

lang/README.md

@@ -965,6 +965,20 @@ main := fn(): uint {
 }
 ```
 
+#### null_check_test
+```hb
+main := fn(): unit {
+	ptr := @as(?^uint, null)
+	*ptr = 0
+
+	if ptr == null {
+		return 1
+	}
+	
+	return *ptr
+}
+```
+
 ### Just Testing Optimizations
 
 #### const_folding_with_arg

lang/src/son.rs

@@ -4058,6 +4058,7 @@ mod tests {
         writing_into_string;
         request_page;
         tests_ptr_to_ptr_copy;
+        null_check_test;
 
         // Just Testing Optimizations;
         const_folding_with_arg;