f2fs: handle error case with f2fs_bug_on

It's enough to show BUG or WARN by f2fs_bug_on for error case.
Then, we don't need to remain corrupted filesystem.

Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/recovery.c

···
 #endif
 				/* We should not get -ENOSPC */
 				f2fs_bug_on(sbi, err);
+				if (err)
+					goto err;
 			}
 
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