BUG: SparseArray.unique fails to keep original elements order

[GYHHAHA]

Pandas version checks

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• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

# 1.4.3
>>> arr = SparseArray([np.nan, 1.0, 0, 0, np.nan, 2], fill_value=1.0)
>>> arr.unique()
[nan, 0.0, 2.0, 1.0]
Fill: 1.0
IntIndex
Indices: array([0, 1, 2])
# main
IndexError: index 5 is out of bounds for axis 0 with size 3

Issue Description

#46287 changes the implementation for SparseArray.unique, which raises for non-default fill_value. (Actually the original one in 1.4.3 is also not correct.)

Expected Behavior

>>> arr.unique()
[nan, 1.0, 0.0, 2.0]
Fill: 1.0
IntIndex
Indices: array([0, 2, 3])

Installed Versions

main