Please address the comments from this code review:

## Overall Comments
- In is_native_reference_point(), you only guard against missing 'REF_Y' but access 'REF_X' unconditionally, which can raise a KeyError for datasets without REF_X; consider checking for 'REF_X' as well or using atr.get with a sensible default.

## Individual Comments

### Comment 1
<location> `src/mintpy/tsview.py:271-274` </location>
<code_context>
+                max_err - int, maximum allowable error to account for
+                          potential geo2radar coordinate conversion error
+    """
+    if 'REF_Y' not in atr.keys():
+        return False
+
+    ref_x = int(atr['REF_X'])
+    ref_y = int(atr['REF_Y'])
+    x0, x1 = ref_x - max_err, ref_x + max_err
</code_context>

<issue_to_address>
**issue:** Guard against missing REF_X key as well as REF_Y when checking native reference point.

This only checks for 'REF_Y' but then indexes atr['REF_X'], which will raise a KeyError if 'REF_X' is missing or misnamed. Please either check for both keys before use (e.g., `if 'REF_X' not in atr or 'REF_Y' not in atr: return False`) or use `atr.get` with a defined fallback to avoid crashes when metadata is incomplete or varies between datasets.
</issue_to_address>

### Comment 2
<location> `src/mintpy/tsview.py:279-282` </location>
<code_context>
def is_native_reference_point(ref_yx, atr, max_err=2):
    """Check if the given ref_yx is the native reference point or not.

    Parameters: ref_yx  - list of int, input reference point in row/col
                atr     - dict, attributes, to retrieve the native REF_Y/X
                max_err - int, maximum allowable error to account for
                          potential geo2radar coordinate conversion error
    """
    if 'REF_Y' not in atr.keys():
        return False

    ref_x = int(atr['REF_X'])
    ref_y = int(atr['REF_Y'])
    x0, x1 = ref_x - max_err, ref_x + max_err
    y0, y1 = ref_y - max_err, ref_y + max_err

    if (x0 <= ref_yx[1] < x1 and y0 <= ref_yx[0] < y1):
        return True
    else:
        return False

</code_context>

<issue_to_address>
**suggestion (code-quality):** We've found these issues:

- Replace if statement with if expression ([`assign-if-exp`](https://docs.sourcery.ai/Reference/Default-Rules/refactorings/assign-if-exp/))
- Simplify boolean if expression ([`boolean-if-exp-identity`](https://docs.sourcery.ai/Reference/Default-Rules/refactorings/boolean-if-exp-identity/))
- Remove unnecessary casts to int, str, float or bool ([`remove-unnecessary-cast`](https://docs.sourcery.ai/Reference/Default-Rules/refactorings/remove-unnecessary-cast/))

```suggestion
    return x0 <= ref_yx[1] < x1 and y0 <= ref_yx[0] < y1
```
</issue_to_address>