Paste relevant section from SQLite documantation

src/inner_connection.rs

@@ -262,8 +262,9 @@ impl InnerConnection {
                 )
             }
         };
+        // If there is an error, *ppStmt is set to NULL.
         self.decode_result(r)?;
-
+        // If the input text contains no SQL (if the input is an empty string or a comment) then *ppStmt is set to NULL.
         let c_stmt: *mut ffi::sqlite3_stmt = unsafe { c_stmt.assume_init() };
         let c_tail: *const c_char = unsafe { c_tail.assume_init() };
         // TODO ignore spaces, comments, ... at the end